├── .gitignore ├── .travis.yml ├── LICENSE ├── README.md ├── allocations ├── README.md ├── pom.xml └── src │ └── main │ ├── java │ └── com │ │ └── github │ │ └── chrishantha │ │ └── sample │ │ └── allocations │ │ └── AllocationsApplication.java │ └── resources │ └── META-INF │ └── services │ └── com.github.chrishantha.sample.base.SampleApplication ├── base ├── README.md ├── pom.xml └── src │ └── main │ └── java │ └── com │ └── github │ └── chrishantha │ └── sample │ └── base │ ├── App.java │ ├── SampleApplication.java │ └── Utils.java ├── deadlock ├── README.md ├── pom.xml └── src │ └── main │ ├── java │ └── com │ │ └── github │ │ └── chrishantha │ │ └── sample │ │ └── deadlock │ │ └── DeadlockApplication.java │ └── resources │ └── META-INF │ └── services │ └── com.github.chrishantha.sample.base.SampleApplication ├── highcpu ├── README.md ├── flame-graphs │ ├── highcpu-jfr.svg │ └── highcpu-perf.svg ├── pom.xml └── src │ └── main │ ├── java │ └── com │ │ └── github │ │ └── chrishantha │ │ └── sample │ │ └── highcpu │ │ ├── HashingWorker.java │ │ ├── HighCpuApplication.java │ │ ├── MathWorker.java │ │ └── SleepingWorker.java │ └── resources │ └── META-INF │ └── services │ └── com.github.chrishantha.sample.base.SampleApplication ├── hotmethods ├── README.md ├── pom.xml └── src │ └── main │ ├── java │ └── com │ │ └── github │ │ └── chrishantha │ │ └── sample │ │ └── hotmethods │ │ └── HotMethodsApplication.java │ └── resources │ └── META-INF │ └── services │ └── com.github.chrishantha.sample.base.SampleApplication ├── latencies ├── README.md ├── pom.xml └── src │ └── main │ ├── java │ └── com │ │ └── github │ │ └── chrishantha │ │ └── sample │ │ └── latencies │ │ └── LatenciesApplication.java │ └── resources │ └── META-INF │ └── services │ └── com.github.chrishantha.sample.base.SampleApplication ├── memoryleak ├── README.md ├── pom.xml └── src │ └── main │ ├── java │ └── com │ │ └── github │ │ └── chrishantha │ │ └── sample │ │ └── memoryleak │ │ ├── BadKey.java │ │ ├── GoodKey.java │ │ ├── Key.java │ │ └── MemoryLeakApplication.java │ └── resources │ └── META-INF │ └── services │ └── com.github.chrishantha.sample.base.SampleApplication ├── memoryref ├── README.md ├── classes.png ├── objects.png ├── pom.xml ├── references.png └── src │ └── main │ ├── java │ └── com │ │ └── github │ │ └── chrishantha │ │ └── sample │ │ └── memoryref │ │ ├── A.java │ │ ├── B.java │ │ ├── Base.java │ │ ├── C.java │ │ ├── D.java │ │ ├── E.java │ │ ├── F.java │ │ ├── G.java │ │ ├── JavaAgent.java │ │ └── MemoryRefApplication.java │ └── resources │ └── META-INF │ └── services │ └── com.github.chrishantha.sample.base.SampleApplication ├── pom.xml └── threadleak ├── README.md ├── pom.xml └── src └── main ├── java └── com │ └── github │ └── chrishantha │ └── sample │ └── threadleak │ └── ThreadLeakApplication.java └── resources └── META-INF └── services └── com.github.chrishantha.sample.base.SampleApplication /.gitignore: -------------------------------------------------------------------------------- 1 | *.class 2 | 3 | # Package Files # 4 | *.jar 5 | *.war 6 | *.ear 7 | 8 | # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml 9 | hs_err_pid* 10 | 11 | #Maven 12 | target/ 13 | dependency-reduced-pom.xml 14 | 15 | #Eclipse files 16 | .project 17 | .classpath 18 | 19 | #Idea Files 20 | .idea 21 | *.iml 22 | 23 | tmp/ 24 | *.tmp 25 | *.bak 26 | *.swp 27 | *~.nib 28 | .settings/ 29 | # Locally stored "Eclipse launch configurations" 30 | *.launch 31 | 32 | # Flight Recorder files 33 | *.jfr 34 | 35 | # Log files 36 | *.log 37 | -------------------------------------------------------------------------------- /.travis.yml: -------------------------------------------------------------------------------- 1 | language: java 2 | jdk: 3 | - openjdk8 4 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright {yyyy} {name of copyright owner} 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | 203 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | [![Build Status](https://travis-ci.org/chrishantha/sample-java-programs.svg?branch=master)](https://travis-ci.org/chrishantha/sample-java-programs) 2 | 3 | Sample Java Programs 4 | ==================== 5 | 6 | This repository contains some sample programs. All are Maven projects and can be run directly using "java -jar" 7 | 8 | ## How to build 9 | 10 | Run `mvn clean install` to build all sample programs 11 | 12 | ## License 13 | 14 | Copyright (C) 2015 M. Isuru Tharanga Chrishantha Perera 15 | 16 | Licensed under the Apache License, Version 2.0 17 | -------------------------------------------------------------------------------- /allocations/README.md: -------------------------------------------------------------------------------- 1 | Sample to show allocations in a Java Flight Recording 2 | ===================================================== 3 | 4 | This program checks whether a number is prime. 5 | 6 | Run the program and also make a profiling recording. 7 | 8 | ### How to run 9 | ```bash 10 | java -Xms64m -Xmx64m -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints -XX:+FlightRecorder -XX:StartFlightRecording=settings=profile,duration=30s,name=Allocations,filename=allocations.jfr -Xlog:jfr=info -jar target/allocations.jar 11 | ``` 12 | 13 | ### Analyzing Java Flight Recording 14 | 15 | In Memory -> Allocation tab, you should see a high allocation rate. 16 | 17 | Also, see Memory -> Garbage Collections tab and check the frequency of GC events. 18 | 19 | ### Improving Performance 20 | 21 | Try the program again after changing `Long` types to primitive `long`. 22 | -------------------------------------------------------------------------------- /allocations/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | ../pom.xml 25 | 26 | 27 | 4.0.0 28 | allocations 29 | jar 30 | allocations 31 | 32 | 33 | 34 | com.github.chrishantha.sample 35 | base 36 | 37 | 38 | 39 | 40 | 41 | 42 | org.apache.maven.plugins 43 | maven-shade-plugin 44 | 45 | 46 | 47 | 48 | -------------------------------------------------------------------------------- /allocations/src/main/java/com/github/chrishantha/sample/allocations/AllocationsApplication.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2017 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.allocations; 17 | 18 | import com.beust.jcommander.Parameter; 19 | import com.github.chrishantha.sample.base.SampleApplication; 20 | 21 | public class AllocationsApplication implements SampleApplication { 22 | 23 | @Parameter(names = "--max", description = "Max Numbers") 24 | private long max = 10_000_000L; 25 | 26 | private boolean isPrime(Long n) { 27 | //check if n is a multiple of 2 28 | if (n % 2 == 0) return false; 29 | //if not, then just check the odds 30 | for (int i = 3; i * i <= n; i += 2) { 31 | if (n % i == 0) 32 | return false; 33 | } 34 | return true; 35 | } 36 | 37 | @Override 38 | public void start() { 39 | Long primeCount = 0L; 40 | for (long i = 0; i < max; i++) { 41 | if (isPrime(i)) { 42 | primeCount++; 43 | } 44 | } 45 | System.out.format("Found %d prime numbers%n", primeCount); 46 | } 47 | 48 | @Override 49 | public String toString() { 50 | return "AllocationsApplication{" + 51 | "max=" + max + 52 | '}'; 53 | } 54 | } 55 | -------------------------------------------------------------------------------- /allocations/src/main/resources/META-INF/services/com.github.chrishantha.sample.base.SampleApplication: -------------------------------------------------------------------------------- 1 | com.github.chrishantha.sample.allocations.AllocationsApplication -------------------------------------------------------------------------------- /base/README.md: -------------------------------------------------------------------------------- 1 | Base module for Sample Applications 2 | =================================== 3 | 4 | This module helps to write sample applications quickly by implementing 5 | `com.github.chrishantha.sample.base.SampleApplication` interface and registering the implementation class as a service 6 | in `META-INF/services/com.github.chrishantha.sample.base.SampleApplication` 7 | -------------------------------------------------------------------------------- /base/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | ../pom.xml 25 | 26 | 27 | 4.0.0 28 | base 29 | jar 30 | base 31 | 32 | 33 | 34 | com.beust 35 | jcommander 36 | 37 | 38 | 39 | -------------------------------------------------------------------------------- /base/src/main/java/com/github/chrishantha/sample/base/App.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.base; 17 | 18 | import com.beust.jcommander.JCommander; 19 | import com.beust.jcommander.Parameter; 20 | import com.beust.jcommander.ParameterException; 21 | 22 | import java.util.Iterator; 23 | import java.util.ServiceLoader; 24 | 25 | public class App { 26 | 27 | private static class CommonArgs { 28 | @Parameter(names = {"-h", "--help"}, description = "Display Help", help = true) 29 | private boolean help = false; 30 | } 31 | 32 | public static void main(String[] args) { 33 | // There should be only one application 34 | Iterator applicationIterator = ServiceLoader.load(SampleApplication.class).iterator(); 35 | if (!applicationIterator.hasNext()) { 36 | throw new IllegalStateException("Could not load Sample Application"); 37 | } 38 | SampleApplication sampleApplication = applicationIterator.next(); 39 | CommonArgs commonArgs = new CommonArgs(); 40 | final JCommander jcmdr = JCommander.newBuilder() 41 | .programName(sampleApplication.getClass().getSimpleName()) 42 | .addObject(sampleApplication) 43 | .addObject(commonArgs) 44 | .build(); 45 | 46 | try { 47 | jcmdr.parse(args); 48 | } catch (ParameterException ex) { 49 | System.err.println(ex.getMessage()); 50 | return; 51 | } 52 | 53 | if (commonArgs.help) { 54 | jcmdr.usage(); 55 | return; 56 | } 57 | 58 | System.out.println(sampleApplication); 59 | sampleApplication.start(); 60 | } 61 | } 62 | -------------------------------------------------------------------------------- /base/src/main/java/com/github/chrishantha/sample/base/SampleApplication.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.base; 17 | 18 | public interface SampleApplication { 19 | 20 | void start(); 21 | 22 | String toString(); 23 | } 24 | -------------------------------------------------------------------------------- /base/src/main/java/com/github/chrishantha/sample/base/Utils.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.base; 17 | 18 | import java.util.Timer; 19 | import java.util.TimerTask; 20 | 21 | /** 22 | * Some basic utilities for sample applications 23 | */ 24 | public class Utils { 25 | 26 | /** 27 | * Exit application after a given number of seconds. 28 | * 29 | * @param timeout Timeout in seconds 30 | */ 31 | public static void exitApplication(int timeout) { 32 | if (timeout > 0) { 33 | final Timer timer = new Timer(); 34 | timer.schedule(new TimerTask() { 35 | public void run() { 36 | System.out.println("Exiting now..."); 37 | System.exit(0); 38 | } 39 | }, timeout * 1000); 40 | } 41 | } 42 | } 43 | -------------------------------------------------------------------------------- /deadlock/README.md: -------------------------------------------------------------------------------- 1 | Sample to show deadlocks in a Java Application 2 | ============================================== 3 | 4 | This sample application shows an example of a deadlock. Following is the definition of "deadlock" according to 5 | [Java Tutorial](https://docs.oracle.com/javase/tutorial/essential/concurrency/deadlock.html) 6 | 7 | > Deadlock describes a situation where two or more threads are blocked forever, waiting for each other. 8 | 9 | In this application, there are two threads trying to acquire two locks. 10 | 11 | ### How to run 12 | 13 | The application will throw Out of Memory error after some time when you run the application with default parameters. 14 | 15 | `java -Xms1g -Xmx1g -jar target/deadlock.jar` 16 | 17 | ### How to detect a deadlock 18 | 19 | Take a thread dump (using `jstack ` command or `jcmd Thread.print`). 20 | 21 | The thread dump should show the Java level deadlock details as follows. 22 | 23 | ``` 24 | Found one Java-level deadlock: 25 | ============================= 26 | "Thread Group 1-2": 27 | waiting to lock monitor 0x00007f8ab4003a78 (object 0x00000000eaca1488, a java.lang.Object), 28 | which is held by "Thread Group 1-1" 29 | "Thread Group 1-1": 30 | waiting to lock monitor 0x00007f8ab4006518 (object 0x00000000eaca1498, a java.lang.Object), 31 | which is held by "Thread Group 1-2" 32 | 33 | Java stack information for the threads listed above: 34 | =================================================== 35 | "Thread Group 1-2": 36 | at com.github.chrishantha.sample.deadlock.DeadlockApplication$SampleLockThread.run(DeadlockApplication.java:54) 37 | - waiting to lock <0x00000000eaca1488> (a java.lang.Object) 38 | - locked <0x00000000eaca1498> (a java.lang.Object) 39 | "Thread Group 1-1": 40 | at com.github.chrishantha.sample.deadlock.DeadlockApplication$SampleLockThread.run(DeadlockApplication.java:54) 41 | - waiting to lock <0x00000000eaca1498> (a java.lang.Object) 42 | - locked <0x00000000eaca1488> (a java.lang.Object) 43 | 44 | Found 1 deadlock. 45 | ``` -------------------------------------------------------------------------------- /deadlock/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | ../pom.xml 25 | 26 | 27 | 4.0.0 28 | deadlock 29 | jar 30 | deadlock 31 | 32 | 33 | 34 | com.github.chrishantha.sample 35 | base 36 | 37 | 38 | 39 | 40 | 41 | 42 | org.apache.maven.plugins 43 | maven-shade-plugin 44 | 45 | 46 | 47 | 48 | -------------------------------------------------------------------------------- /deadlock/src/main/java/com/github/chrishantha/sample/deadlock/DeadlockApplication.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.deadlock; 17 | 18 | import com.beust.jcommander.Parameter; 19 | import com.github.chrishantha.sample.base.SampleApplication; 20 | 21 | public class DeadlockApplication implements SampleApplication { 22 | 23 | @Parameter(names = "--count", description = "Number of deadlocks") 24 | private int count = 1; 25 | 26 | @Parameter(names = "--delay", description = "Delay in milliseconds to start a new thread group") 27 | private int delay = 0; 28 | 29 | private static class SampleLockThread extends Thread { 30 | 31 | private final Object lock1; 32 | private final Object lock2; 33 | 34 | public SampleLockThread(final String name, final Object lock1, final Object lock2) { 35 | super(name); 36 | this.lock1 = lock1; 37 | this.lock2 = lock2; 38 | } 39 | 40 | @Override 41 | public void run() { 42 | System.out.format("%s: Acquiring lock : %s%n", getName(), lock1); 43 | synchronized (lock1) { 44 | System.out.format("%s: Acquired lock : %s%n", getName(), lock1); 45 | try { 46 | Thread.sleep(100); 47 | } catch (InterruptedException e) { 48 | e.printStackTrace(); 49 | } 50 | 51 | System.out.format("%s: Acquiring lock : %s%n", getName(), lock2); 52 | synchronized (lock2) { 53 | System.out.format("%s: Acquired lock : %s%n", getName(), lock2); 54 | 55 | } 56 | } 57 | } 58 | } 59 | 60 | @Override 61 | public void start() { 62 | final String nameFormat = "Thread Group %2d-%d"; 63 | for (int i = 1; i <= count; i++) { 64 | final Object lock1 = new Object(); 65 | final Object lock2 = new Object(); 66 | SampleLockThread t1 = new SampleLockThread(String.format(nameFormat, i, 1), lock1, lock2); 67 | SampleLockThread t2 = new SampleLockThread(String.format(nameFormat, i, 2), lock2, lock1); 68 | t1.start(); 69 | t2.start(); 70 | if (delay > 0) { 71 | try { 72 | Thread.sleep(delay); 73 | } catch (InterruptedException e) { 74 | e.printStackTrace(); 75 | } 76 | } 77 | } 78 | } 79 | 80 | @Override 81 | public String toString() { 82 | return "DeadlockApplication{" + 83 | "count=" + count + 84 | ", delay=" + delay + 85 | '}'; 86 | } 87 | } 88 | -------------------------------------------------------------------------------- /deadlock/src/main/resources/META-INF/services/com.github.chrishantha.sample.base.SampleApplication: -------------------------------------------------------------------------------- 1 | com.github.chrishantha.sample.deadlock.DeadlockApplication -------------------------------------------------------------------------------- /highcpu/README.md: -------------------------------------------------------------------------------- 1 | Sample program consuming high CPU usage 2 | ======================================= 3 | 4 | A java program consuming high CPU usage. This program was inspired by a sample found in the article "[Identifying which Java Thread is consuming most CPU](http://code.nomad-labs.com/2010/11/18/identifying-which-java-thread-is-consuming-most-cpu/)" 5 | 6 | ### How to run 7 | ```bash 8 | java -Xms128m -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints -XX:+FlightRecorder -XX:StartFlightRecording=settings=profile,duration=30s,name=HighCPU,filename=highcpu.jfr -Xlog:jfr=info -jar target/highcpu.jar 9 | ``` 10 | -------------------------------------------------------------------------------- /highcpu/flame-graphs/highcpu-jfr.svg: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 14 | 333 | 334 | Flame Graph 335 | 336 | Reset Zoom 337 | Search 338 | 339 | 340 | java.util.Arrays.copyOfRange(char[], int, int) (5 samples, 0.14%) 341 | 342 | 343 | 344 | java.lang.StringBuilder.(init)() (43 samples, 1.19%) 345 | 346 | 347 | 348 | sun.misc.FloatingDecimal$BinaryToASCIIBuffer.access$100(sun.misc.FloatingDecimal$BinaryToASCIIBuffer, int, long, int, boolean) (1,211 samples, 33.38%) 349 | sun.misc.FloatingDecimal$BinaryToASCIIBuffer.access$100(sun.misc.FloatingDec.. 350 | 351 | 352 | java.lang.StringBuilder.append(java.lang.String) (224 samples, 6.17%) 353 | java.lang.St.. 354 | 355 | 356 | java.math.BigDecimal.(init)(char[], int, int, java.math.MathContext) (442 samples, 12.18%) 357 | java.math.BigDecimal.(init.. 358 | 359 | 360 | java.lang.String.(init)(char[], int, int) (5 samples, 0.14%) 361 | 362 | 363 | 364 | oracle.jrockit.jfr.JFRImpl.dumpOnExit() (1 samples, 0.03%) 365 | 366 | 367 | 368 | java.security.MessageDigest$Delegate.engineUpdate(byte[], int, int) (16 samples, 0.44%) 369 | 370 | 371 | 372 | sun.security.provider.DigestBase.implCompressMultiBlock(byte[], int, int) (16 samples, 0.44%) 373 | 374 | 375 | 376 | sun.misc.FloatingDecimal$BinaryToASCIIBuffer.dtoa(int, long, int, boolean) (1,111 samples, 30.62%) 377 | sun.misc.FloatingDecimal$BinaryToASCIIBuffer.dtoa(int, long, int, boo.. 378 | 379 | 380 | java.lang.Thread.run() (3,628 samples, 100.00%) 381 | java.lang.Thread.run() 382 | 383 | 384 | sun.security.provider.NativePRNG$RandomIO.implNextBytes(byte[]) (76 samples, 2.09%) 385 | su.. 386 | 387 | 388 | java.lang.AbstractStringBuilder.append(java.lang.String) (223 samples, 6.15%) 389 | java.lang.Ab.. 390 | 391 | 392 | java.lang.StringCoding.encode(char[], int, int) (4 samples, 0.11%) 393 | 394 | 395 | 396 | java.math.BigDecimal.add(long, int, java.math.BigInteger, int) (132 samples, 3.64%) 397 | java.m.. 398 | 399 | 400 | sun.security.jca.GetInstance.getInstance(java.lang.String, java.lang.Class, java.lang.String) (1 samples, 0.03%) 401 | 402 | 403 | 404 | sun.security.provider.DigestBase.engineUpdate(byte[], int, int) (16 samples, 0.44%) 405 | 406 | 407 | 408 | oracle.jrockit.jfr.Settings$Aggregator.copy(oracle.jrockit.jfr.Settings$Aggregator) (1 samples, 0.03%) 409 | 410 | 411 | 412 | sun.security.provider.ByteArrayAccess.b2iBig64(byte[], int, int[]) (1 samples, 0.03%) 413 | 414 | 415 | 416 | java.util.Random.nextDouble() (1 samples, 0.03%) 417 | 418 | 419 | 420 | java.security.MessageDigest.update(byte[]) (16 samples, 0.44%) 421 | 422 | 423 | 424 | sun.misc.FloatingDecimal.getBinaryToASCIIBuffer() (43 samples, 1.19%) 425 | 426 | 427 | 428 | sun.security.provider.NativePRNG$RandomIO.readFully(java.io.InputStream, byte[]) (2 samples, 0.06%) 429 | 430 | 431 | 432 | java.math.BigDecimal.add(java.math.BigDecimal) (137 samples, 3.78%) 433 | java.m.. 434 | 435 | 436 | java.lang.String.getChars(int, int, char[], int) (8 samples, 0.22%) 437 | 438 | 439 | 440 | java.security.Security.getImpl(java.lang.String, java.lang.String, java.lang.String) (1 samples, 0.03%) 441 | 442 | 443 | 444 | oracle.jrockit.jfr.JFRImpl.destroy() (1 samples, 0.03%) 445 | 446 | 447 | 448 | java.lang.ThreadLocal$ThreadLocalMap.access$000(java.lang.ThreadLocal$ThreadLocalMap, java.lang.ThreadLocal) (42 samples, 1.16%) 449 | 450 | 451 | 452 | java.security.MessageDigest$Delegate.engineDigest() (46 samples, 1.27%) 453 | 454 | 455 | 456 | java.math.BigDecimal.valueOf(java.math.BigInteger, int, int) (17 samples, 0.47%) 457 | 458 | 459 | 460 | sun.security.provider.DigestBase.engineDigest(byte[], int, int) (46 samples, 1.27%) 461 | 462 | 463 | 464 | java.lang.StringBuilder.append(java.lang.String) (1 samples, 0.03%) 465 | 466 | 467 | 468 | sun.security.jca.GetInstance.getInstance(java.security.Provider$Service, java.lang.Class) (1 samples, 0.03%) 469 | 470 | 471 | 472 | java.lang.StringBuilder.toString() (6 samples, 0.17%) 473 | 474 | 475 | 476 | sun.misc.FloatingDecimal.getBinaryToASCIIConverter(double, boolean) (1,254 samples, 34.56%) 477 | sun.misc.FloatingDecimal.getBinaryToASCIIConverter(double, boolean) 478 | 479 | 480 | com.oracle.jrockit.jfr.EventToken.isEnabled() (1 samples, 0.03%) 481 | 482 | 483 | 484 | java.math.BigDecimal.valueOf(double) (1,839 samples, 50.69%) 485 | java.math.BigDecimal.valueOf(double) 486 | 487 | 488 | java.lang.AbstractStringBuilder.expandCapacity(int) (1 samples, 0.03%) 489 | 490 | 491 | 492 | sun.security.provider.SecureRandom.updateState(byte[], byte[]) (1 samples, 0.03%) 493 | 494 | 495 | 496 | java.lang.String.getBytes() (4 samples, 0.11%) 497 | 498 | 499 | 500 | java.lang.ThreadLocal.get() (43 samples, 1.19%) 501 | 502 | 503 | 504 | java.lang.Double.toString(double) (1,312 samples, 36.16%) 505 | java.lang.Double.toString(double) 506 | 507 | 508 | oracle.jrockit.jfr.JFRImpl.dumpOnExit(oracle.jrockit.jfr.Recording) (1 samples, 0.03%) 509 | 510 | 511 | 512 | java.math.BigDecimal.add(long, long, int) (1 samples, 0.03%) 513 | 514 | 515 | 516 | java.lang.AbstractStringBuilder.append(java.lang.String) (1 samples, 0.03%) 517 | 518 | 519 | 520 | java.security.SecureRandom.nextBytes(byte[]) (530 samples, 14.61%) 521 | java.security.SecureRandom.nextB.. 522 | 523 | 524 | sun.security.provider.DigestBase.engineDigest() (46 samples, 1.27%) 525 | 526 | 527 | 528 | java.util.Arrays.copyOf(char[], int) (211 samples, 5.82%) 529 | java.util.A.. 530 | 531 | 532 | java.lang.Long.formatUnsignedLong(long, int, char[], int, int) (5 samples, 0.14%) 533 | 534 | 535 | 536 | java.lang.AbstractStringBuilder.expandCapacity(int) (211 samples, 5.82%) 537 | java.lang.A.. 538 | 539 | 540 | java.math.BigInteger.negate() (1 samples, 0.03%) 541 | 542 | 543 | 544 | com.github.chrishantha.sample.highcpu.MathWorker.run() (2,462 samples, 67.86%) 545 | com.github.chrishantha.sample.highcpu.MathWorker.run() 546 | 547 | 548 | java.math.BigInteger.add(long) (89 samples, 2.45%) 549 | jav.. 550 | 551 | 552 | java.lang.AbstractStringBuilder.(init)(int) (43 samples, 1.19%) 553 | 554 | 555 | 556 | java.security.MessageDigest.getInstance(java.lang.String) (1 samples, 0.03%) 557 | 558 | 559 | 560 | sun.security.provider.ByteArrayAccess.b2iBig64(byte[], int, int[]) (4 samples, 0.11%) 561 | 562 | 563 | 564 | java.lang.ThreadLocal$ThreadLocalMap.getEntry(java.lang.ThreadLocal) (42 samples, 1.16%) 565 | 566 | 567 | 568 | oracle.jrockit.jfr.Settings$Aggregator.mergeDefaults(java.util.Collection, java.util.Map) (1 samples, 0.03%) 569 | 570 | 571 | 572 | java.math.BigInteger.compareMagnitude(long) (41 samples, 1.13%) 573 | 574 | 575 | 576 | java.math.BigDecimal.valueOf(java.math.BigInteger, int, int) (94 samples, 2.59%) 577 | java.. 578 | 579 | 580 | sun.security.provider.SecureRandom.engineNextBytes(byte[]) (59 samples, 1.63%) 581 | s.. 582 | 583 | 584 | java.lang.Long.toUnsignedString0(long, int) (5 samples, 0.14%) 585 | 586 | 587 | 588 | java.io.FileInputStream.read(byte[], int, int) (2 samples, 0.06%) 589 | 590 | 591 | 592 | java.lang.StringCoding.encode(java.lang.String, char[], int, int) (4 samples, 0.11%) 593 | 594 | 595 | 596 | java.lang.Math.atan(double) (336 samples, 9.26%) 597 | java.lang.Math.atan.. 598 | 599 | 600 | sun.security.provider.ByteArrayAccess.i2bBig4(int, byte[], int) (13 samples, 0.36%) 601 | 602 | 603 | 604 | java.util.UUID.randomUUID() (531 samples, 14.64%) 605 | java.util.UUID.randomUUID() 606 | 607 | 608 | java.math.BigDecimal.add(long, int, long, int) (1 samples, 0.03%) 609 | 610 | 611 | 612 | oracle.jrockit.jfr.Settings$Aggregator.updateDefaults(java.util.Collection) (1 samples, 0.03%) 613 | 614 | 615 | 616 | sun.security.provider.SHA.implDigest(byte[], int) (46 samples, 1.27%) 617 | 618 | 619 | 620 | oracle.jrockit.jfr.Settings$Aggregator.updateDefaults() (1 samples, 0.03%) 621 | 622 | 623 | 624 | java.lang.StringCoding$StringEncoder.encode(char[], int, int) (4 samples, 0.11%) 625 | 626 | 627 | 628 | java.math.BigDecimal.subtract(java.math.BigDecimal) (134 samples, 3.69%) 629 | java.m.. 630 | 631 | 632 | java.math.BigDecimal.valueOf(long, int) (1 samples, 0.03%) 633 | 634 | 635 | 636 | java.util.UUID.digits(long, int) (5 samples, 0.14%) 637 | 638 | 639 | 640 | com.oracle.jrockit.jfr.DurationEvent.begin() (1 samples, 0.03%) 641 | 642 | 643 | 644 | sun.misc.FloatingDecimal.getBinaryToASCIIConverter(double) (1,254 samples, 34.56%) 645 | sun.misc.FloatingDecimal.getBinaryToASCIIConverter(double) 646 | 647 | 648 | java.math.BigDecimal.add(long, int, java.math.BigInteger, int) (136 samples, 3.75%) 649 | java.m.. 650 | 651 | 652 | sun.security.provider.NativePRNG$RandomIO.ensureBufferValid() (3 samples, 0.08%) 653 | 654 | 655 | 656 | java.math.BigInteger.add(int[], long) (2 samples, 0.06%) 657 | 658 | 659 | 660 | java.math.BigDecimal.add(long, int, long, int) (1 samples, 0.03%) 661 | 662 | 663 | 664 | oracle.jrockit.jfr.Settings$Aggregator.replaceEventDefaultSets(java.util.Collection) (1 samples, 0.03%) 665 | 666 | 667 | 668 | java.lang.AbstractStringBuilder.ensureCapacityInternal(int) (211 samples, 5.82%) 669 | java.lang.A.. 670 | 671 | 672 | sun.security.provider.NativePRNG.engineNextBytes(byte[]) (499 samples, 13.75%) 673 | sun.security.provider.NativePR.. 674 | 675 | 676 | sun.security.provider.SHA.implCompress(byte[], int) (31 samples, 0.85%) 677 | 678 | 679 | 680 | java.math.BigDecimal.(init)(char[], int, int) (527 samples, 14.53%) 681 | java.math.BigDecimal.(init)(char.. 682 | 683 | 684 | sun.misc.FloatingDecimal$BinaryToASCIIBuffer.toJavaFormatString() (57 samples, 1.57%) 685 | s.. 686 | 687 | 688 | java.security.MessageDigest.digest() (46 samples, 1.27%) 689 | 690 | 691 | 692 | java.math.BigInteger.compareMagnitude(long) (86 samples, 2.37%) 693 | jav.. 694 | 695 | 696 | oracle.jrockit.jfr.JFRImpl.cloneRecording(oracle.jrockit.jfr.Recording, java.lang.String, boolean) (1 samples, 0.03%) 697 | 698 | 699 | 700 | java.util.Random.nextInt(int) (2 samples, 0.06%) 701 | 702 | 703 | 704 | java.math.BigInteger.add(long) (41 samples, 1.13%) 705 | 706 | 707 | 708 | java.math.BigDecimal.(init)(java.lang.String) (527 samples, 14.53%) 709 | java.math.BigDecimal.(init)(java.. 710 | 711 | 712 | java.lang.String.(init)(char[], int, int) (2 samples, 0.06%) 713 | 714 | 715 | 716 | java.util.Arrays.copyOfRange(char[], int, int) (2 samples, 0.06%) 717 | 718 | 719 | 720 | java.util.UUID.toString() (49 samples, 1.35%) 721 | j.. 722 | 723 | 724 | java.lang.Long.toHexString(long) (5 samples, 0.14%) 725 | 726 | 727 | 728 | java.lang.String.equals(java.lang.Object) (1 samples, 0.03%) 729 | 730 | 731 | 732 | sun.misc.FloatingDecimal.toJavaFormatString(double) (1,312 samples, 36.16%) 733 | sun.misc.FloatingDecimal.toJavaFormatString(double) 734 | 735 | 736 | java.util.Arrays.copyOf(char[], int) (1 samples, 0.03%) 737 | 738 | 739 | 740 | oracle.jrockit.jfr.Settings$Aggregator.getDefault(com.oracle.jrockit.jfr.EventInfo) (1 samples, 0.03%) 741 | 742 | 743 | 744 | java.lang.AbstractStringBuilder.ensureCapacityInternal(int) (1 samples, 0.03%) 745 | 746 | 747 | 748 | sun.security.provider.SHA.implCompress(byte[], int) (16 samples, 0.44%) 749 | 750 | 751 | 752 | sun.misc.FloatingDecimal$BinaryToASCIIBuffer.getChars(char[]) (45 samples, 1.24%) 753 | 754 | 755 | 756 | all (3,628 samples, 100%) 757 | 758 | 759 | 760 | com.github.chrishantha.sample.highcpu.HashingWorker.run() (1,165 samples, 32.11%) 761 | com.github.chrishantha.sample.highcpu.HashingWorker.run() 762 | 763 | 764 | sun.nio.cs.UTF_8$Encoder.encode(char[], int, int, byte[]) (4 samples, 0.11%) 765 | 766 | 767 | 768 | java.math.BigDecimal.add(long, long, int) (1 samples, 0.03%) 769 | 770 | 771 | 772 | oracle.jrockit.jfr.JFR$2.run() (1 samples, 0.03%) 773 | 774 | 775 | 776 | sun.security.provider.NativePRNG$RandomIO.access$400(sun.security.provider.NativePRNG$RandomIO, byte[]) (499 samples, 13.75%) 777 | sun.security.provider.NativePR.. 778 | 779 | 780 | -------------------------------------------------------------------------------- /highcpu/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | ../pom.xml 25 | 26 | 27 | 4.0.0 28 | highcpu 29 | jar 30 | highcpu 31 | 32 | 33 | 34 | com.github.chrishantha.sample 35 | base 36 | 37 | 38 | 39 | 40 | 41 | 42 | org.apache.maven.plugins 43 | maven-shade-plugin 44 | 45 | 46 | 47 | 48 | -------------------------------------------------------------------------------- /highcpu/src/main/java/com/github/chrishantha/sample/highcpu/HashingWorker.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2015 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.highcpu; 17 | 18 | import java.security.MessageDigest; 19 | import java.security.NoSuchAlgorithmException; 20 | import java.util.UUID; 21 | 22 | public class HashingWorker implements Runnable { 23 | 24 | private final String algorithm; 25 | private final long length; 26 | 27 | private byte[] lastComputedHash; 28 | 29 | public HashingWorker(long length, String algorithm) { 30 | this.length = length; 31 | this.algorithm = algorithm; 32 | } 33 | 34 | @SuppressWarnings("InfiniteLoopStatement") 35 | @Override 36 | public void run() { 37 | while (true) { 38 | StringBuilder data = new StringBuilder(); 39 | 40 | // Some random data 41 | for (int i = 0; i < length; i++) { 42 | data.append(UUID.randomUUID().toString()); 43 | } 44 | 45 | MessageDigest digest; 46 | try { 47 | digest = MessageDigest.getInstance(algorithm); 48 | } catch (NoSuchAlgorithmException e) { 49 | throw new RuntimeException(e); 50 | } 51 | 52 | // Hash 53 | digest.update(data.toString().getBytes()); 54 | byte[] computedHash = digest.digest(); 55 | if (lastComputedHash != null && computedHash.length != lastComputedHash.length) { 56 | throw new IllegalStateException("Is the hash computation correct??"); 57 | } 58 | lastComputedHash = computedHash; 59 | } 60 | } 61 | } 62 | -------------------------------------------------------------------------------- /highcpu/src/main/java/com/github/chrishantha/sample/highcpu/HighCpuApplication.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2015 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.highcpu; 17 | 18 | import com.beust.jcommander.Parameter; 19 | import com.github.chrishantha.sample.base.SampleApplication; 20 | import com.github.chrishantha.sample.base.Utils; 21 | 22 | public class HighCpuApplication implements SampleApplication { 23 | 24 | @Parameter(names = "--run-hashing", description = "Run Hashing Worker", arity = 1) 25 | private boolean runHashing = true; 26 | 27 | @Parameter(names = "--run-sleeping", description = "Run Sleeping Worker", arity = 1) 28 | private boolean runSleeping = true; 29 | 30 | @Parameter(names = "--run-math", description = "Run Math Worker", arity = 1) 31 | private boolean runMath = true; 32 | 33 | @Parameter(names = "--hashing-workers", description = "Hashing Workers") 34 | private int hashingWorkers = 6; 35 | 36 | @Parameter(names = "--sleeping-workers", description = "Sleeping Workers") 37 | private int sleepingWorkers = 4; 38 | 39 | @Parameter(names = "--math-workers", description = "Math Workers") 40 | private int mathWorkers = 2; 41 | 42 | @Parameter(names = "--hash-data-length", description = "Hash Data Length") 43 | private long hashDataLength = 2000; 44 | 45 | @Parameter(names = "--hashing-algo", description = "Hashing Algorithm") 46 | private String hashingAlgorithm = "SHA-1"; 47 | 48 | @Parameter(names = "--exit-timeout", description = "Exit Timeout in Seconds (Default 2 minutes. Use 0 to run forever)") 49 | private int exitTimeoutInSeconds = 2 * 60; 50 | 51 | @Override 52 | public void start() { 53 | System.out.println("Starting Application..."); 54 | Utils.exitApplication(exitTimeoutInSeconds); 55 | if (runHashing) { 56 | for (int i = 0; i < hashingWorkers; i++) { 57 | startThread(i, "Hashing", new HashingWorker(hashDataLength, hashingAlgorithm)); 58 | } 59 | } 60 | if (runSleeping) { 61 | for (int i = 0; i < sleepingWorkers; i++) { 62 | startThread(i, "Sleeping", new SleepingWorker()); 63 | } 64 | } 65 | if (runMath) { 66 | for (int i = 0; i < mathWorkers; i++) { 67 | startThread(i, "Math", new MathWorker()); 68 | } 69 | } 70 | } 71 | 72 | private void startThread(int i, String name, Runnable worker) { 73 | Thread thread = new Thread(worker); 74 | thread.setName(String.format("Thread %d: %s", i, name)); 75 | thread.start(); 76 | } 77 | 78 | @Override 79 | public String toString() { 80 | return "HighCpuApplication{" + 81 | "runHashing=" + runHashing + 82 | ", runSleeping=" + runSleeping + 83 | ", runMath=" + runMath + 84 | ", hashingWorkers=" + hashingWorkers + 85 | ", sleepingWorkers=" + sleepingWorkers + 86 | ", mathWorkers=" + mathWorkers + 87 | ", hashDataLength=" + hashDataLength + 88 | ", hashingAlgorithm='" + hashingAlgorithm + '\'' + 89 | ", exitTimeoutInSeconds=" + exitTimeoutInSeconds + 90 | '}'; 91 | } 92 | } 93 | -------------------------------------------------------------------------------- /highcpu/src/main/java/com/github/chrishantha/sample/highcpu/MathWorker.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2015 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.highcpu; 17 | 18 | import java.math.BigDecimal; 19 | import java.util.Random; 20 | 21 | public class MathWorker implements Runnable { 22 | 23 | private Random random = new Random(); 24 | 25 | @SuppressWarnings("InfiniteLoopStatement") 26 | @Override 27 | public void run() { 28 | BigDecimal bigDecimal = BigDecimal.ZERO; 29 | while (true) { 30 | double value = Math.atan(Math.sqrt(Math.pow(random.nextInt(10), random.nextDouble()))); 31 | if (random.nextInt(10) > 5) { 32 | bigDecimal = bigDecimal.add(BigDecimal.valueOf(value)); 33 | } else { 34 | bigDecimal = bigDecimal.subtract(BigDecimal.valueOf(value)); 35 | } 36 | } 37 | } 38 | } 39 | -------------------------------------------------------------------------------- /highcpu/src/main/java/com/github/chrishantha/sample/highcpu/SleepingWorker.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2015 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.highcpu; 17 | 18 | import java.util.Random; 19 | 20 | public class SleepingWorker implements Runnable { 21 | 22 | private Random random = new Random(); 23 | 24 | @SuppressWarnings("InfiniteLoopStatement") 25 | @Override 26 | public void run() { 27 | Long l = 0L; 28 | while (true) { 29 | l++; 30 | try { 31 | Thread.sleep(random.nextInt(20)); 32 | } catch (InterruptedException e) { 33 | e.printStackTrace(); 34 | } 35 | if (l == Long.MAX_VALUE) { 36 | l = 0L; 37 | } 38 | } 39 | } 40 | } 41 | -------------------------------------------------------------------------------- /highcpu/src/main/resources/META-INF/services/com.github.chrishantha.sample.base.SampleApplication: -------------------------------------------------------------------------------- 1 | com.github.chrishantha.sample.highcpu.HighCpuApplication -------------------------------------------------------------------------------- /hotmethods/README.md: -------------------------------------------------------------------------------- 1 | Sample to show hot methods in a Java Flight Recording 2 | ===================================================== 3 | 4 | This program checks whether a given random number is primitive or not. 5 | 6 | Run the program and also make a profiling recording. 7 | 8 | ### How to run 9 | ```bash 10 | java -Xms64m -Xmx64m -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints -XX:+FlightRecorder -XX:StartFlightRecording=settings=profile,duration=60s,name=Hotmethods,filename=hotmethods.jfr -Xlog:jfr=info -jar target/hotmethods.jar 11 | ``` 12 | 13 | ### Analyzing Java Flight Recording 14 | 15 | In Code -> Hot Methods tab, you should see that the program has spent a lot of time in the LinkedList.indexOf(Object) method, which is called from contains method. 16 | 17 | ### Improving Performance 18 | 19 | By changing LinkedList to a HashSet, you can make the program run a lot faster. 20 | 21 | The contains methods in Linked List checks all the items. Algorithm run time is O(n). However the HashSet contains algorithm's run time is O(1). 22 | 23 | In the program, change `Collection primeNumbers = new LinkedList<>()` to `Collection primeNumbers = new HashSet<>()` to use a HashSet for Prime Numbers 24 | 25 | Check the runtime using HashSet. 26 | 27 | Use `time` command in Linux to measure the time. 28 | -------------------------------------------------------------------------------- /hotmethods/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | ../pom.xml 25 | 26 | 27 | 4.0.0 28 | hotmethods 29 | jar 30 | hotmethods 31 | 32 | 33 | 34 | com.github.chrishantha.sample 35 | base 36 | 37 | 38 | 39 | 40 | 41 | 42 | org.apache.maven.plugins 43 | maven-shade-plugin 44 | 45 | 46 | 47 | 48 | -------------------------------------------------------------------------------- /hotmethods/src/main/java/com/github/chrishantha/sample/hotmethods/HotMethodsApplication.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2017 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.hotmethods; 17 | 18 | import com.beust.jcommander.Parameter; 19 | import com.github.chrishantha.sample.base.SampleApplication; 20 | 21 | import java.util.Collection; 22 | import java.util.LinkedList; 23 | import java.util.Random; 24 | 25 | public class HotMethodsApplication implements SampleApplication { 26 | 27 | @Parameter(names = "--count", description = "Random Numbers Count") 28 | private int randomNumbersCount = 1000000; 29 | 30 | @Parameter(names = "--max", description = "Maximum limit to generate prime numbers") 31 | private int max = 100000; 32 | 33 | @Override 34 | public void start() { 35 | Collection primeNumbers = new LinkedList<>(); 36 | System.out.println("Generating Prime numbers between 1 and " + max); 37 | for (int i = 1; i < max; i++) { 38 | boolean isPrimeNumber = true; 39 | // Check whether the number is prime 40 | for (int j = 2; j < i; j++) { 41 | if (i % j == 0) { 42 | isPrimeNumber = false; 43 | break; 44 | } 45 | } 46 | 47 | if (isPrimeNumber) { 48 | primeNumbers.add(i); 49 | } 50 | } 51 | 52 | Random random = new Random(); 53 | System.out.println("Checking Random Prime numbers"); 54 | int count = 0; 55 | for (int i = 1; i < randomNumbersCount; i++) { 56 | int randomNumber = random.nextInt(max); 57 | if (primeNumbers.contains(randomNumber)) { 58 | count++; 59 | } 60 | } 61 | System.out.format("Found %d prime numbers from %d random numbers%n", count, randomNumbersCount); 62 | } 63 | 64 | @Override 65 | public String toString() { 66 | return "HotMethodsApplication{" + 67 | "randomNumbersCount=" + randomNumbersCount + 68 | ", max=" + max + 69 | '}'; 70 | } 71 | } 72 | -------------------------------------------------------------------------------- /hotmethods/src/main/resources/META-INF/services/com.github.chrishantha.sample.base.SampleApplication: -------------------------------------------------------------------------------- 1 | com.github.chrishantha.sample.hotmethods.HotMethodsApplication -------------------------------------------------------------------------------- /latencies/README.md: -------------------------------------------------------------------------------- 1 | Sample to show latencies in a Java Flight Recording 2 | =================================================== 3 | 4 | This program has two threads: Even and Odd to print Even and Odd numbers. 5 | 6 | Run the program and also make a profiling recording. 7 | 8 | ### How to run 9 | ```bash 10 | java -Xms64m -Xmx64m -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints -XX:+FlightRecorder -XX:StartFlightRecording=settings=profile,duration=30s,name=Latencies,filename=latencies.jfr -Xlog:jfr=info -jar target/latencies.jar 11 | ``` 12 | 13 | ### Analyzing Java Flight Recording 14 | 15 | In Threads -> Latencies tab, you should see that the program has many blocked events. 16 | 17 | You should also see red blocks in Events -> Graph tab. Red blocks are not good as the thread is just waiting to acquire a lock. 18 | 19 | See Threads -> Contention tab to see the Locks and also see Threads -> Lock Instances to check whether both threads share the same lock instances. 20 | 21 | ### Improving Performance 22 | 23 | Since there is no shared resource to protect, you can avoid the synchronized keyword and improve the performance. 24 | 25 | Try the program again after removing the `synchronized` keyword in `isEven` method. 26 | -------------------------------------------------------------------------------- /latencies/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | ../pom.xml 25 | 26 | 27 | 4.0.0 28 | latencies 29 | jar 30 | latencies 31 | 32 | 33 | 34 | com.github.chrishantha.sample 35 | base 36 | 37 | 38 | 39 | 40 | 41 | 42 | org.apache.maven.plugins 43 | maven-shade-plugin 44 | 45 | 46 | 47 | 48 | -------------------------------------------------------------------------------- /latencies/src/main/java/com/github/chrishantha/sample/latencies/LatenciesApplication.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2017 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.latencies; 17 | 18 | import com.beust.jcommander.Parameter; 19 | import com.github.chrishantha.sample.base.SampleApplication; 20 | 21 | public class LatenciesApplication implements SampleApplication { 22 | 23 | @Parameter(names = "--count", description = "Print Count") 24 | private int count = 50; 25 | 26 | private class EvenThread extends Thread { 27 | 28 | public EvenThread() { 29 | super("Even-Thread"); 30 | } 31 | 32 | @Override 33 | public void run() { 34 | for (int i = 0; i < count; i++) { 35 | if (isEven(i)) { 36 | printNumber(i); 37 | } 38 | } 39 | } 40 | } 41 | 42 | private class OddThread extends Thread { 43 | 44 | public OddThread() { 45 | super("Odd-Thread"); 46 | } 47 | 48 | @Override 49 | public void run() { 50 | for (int i = 0; i < count; i++) { 51 | if (!isEven(i)) { 52 | printNumber(i); 53 | } 54 | } 55 | } 56 | } 57 | 58 | 59 | private void printNumber(int i) { 60 | System.out.format("Thread: %s, Number: %d%n", Thread.currentThread().getName(), i); 61 | } 62 | 63 | private synchronized boolean isEven(int i) { 64 | try { 65 | Thread.sleep(1000); 66 | } catch (InterruptedException e) { 67 | e.printStackTrace(); 68 | } 69 | return i % 2 == 0; 70 | } 71 | 72 | @Override 73 | public void start() { 74 | new EvenThread().start(); 75 | new OddThread().start(); 76 | } 77 | 78 | @Override 79 | public String toString() { 80 | return "LatenciesApplication{" + 81 | "count=" + count + 82 | '}'; 83 | } 84 | } 85 | -------------------------------------------------------------------------------- /latencies/src/main/resources/META-INF/services/com.github.chrishantha.sample.base.SampleApplication: -------------------------------------------------------------------------------- 1 | com.github.chrishantha.sample.latencies.LatenciesApplication -------------------------------------------------------------------------------- /memoryleak/README.md: -------------------------------------------------------------------------------- 1 | Sample to show a memory leak in Java Application 2 | ================================================ 3 | 4 | This sample application implements a simple caching solution using a `HashMap`. 5 | 6 | For example, see following code. 7 | 8 | Map map = new HashMap<>(); 9 | while (true) { 10 | for (int i = 0; i < max; i++) { 11 | Key key = new Key(i); 12 | if (!map.containsKey(key)) { 13 | map.put(key, "Number:" + i); 14 | } 15 | } 16 | } 17 | 18 | The map is not expected to grow beyond `max` value as all keys will be there in the map after the first `while` loop. 19 | 20 | However, if the `Key` class does not contain a proper `equals()` implementation along with the `hashCode()` 21 | implementation, the key elements will be keep getting added as the `!map.containsKey(key)` will always return `false`. 22 | This is a good example of a memory leak and this sample was inspired by the blog post: 23 | "[How to create a memory leak](https://plumbr.io/blog/memory-leaks/how-to-create-a-memory-leak)" 24 | 25 | ### How to run 26 | 27 | The application will throw Out of Memory error after some time when you run following command 28 | 29 | `java -Xms1g -Xmx1g -XX:+PrintGCDetails -XX:+PrintGC -XX:+PrintGCDateStamps -Xloggc:gc.log 30 | -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath="/tmp/heap-dump.hprof" 31 | -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints 32 | -XX:+UnlockCommercialFeatures -XX:+FlightRecorder 33 | -XX:StartFlightRecording=settings=profile,duration=5m,name=MemoryLeak,filename=memoryleak.jfr 34 | -XX:FlightRecorderOptions=loglevel=info 35 | -jar target/memoryleak.jar` 36 | 37 | ### Analyzing Java Flight Recording 38 | 39 | In Memory -> Memory tab, you should see a high memory growth rate. 40 | 41 | Also see Memory -> Garbage Collections tab and check the frequency of GC events. 42 | 43 | ### Analyzing Garbage Collection Logs (GC) 44 | 45 | You can analyze the GC logs using [GCViewer](https://github.com/chewiebug/GCViewer) 46 | 47 | ### How to fix the Memory Leak 48 | 49 | Run the application with `--key-type GOOD` parameter, which will use a Key object with proper `equals()` implementation. 50 | -------------------------------------------------------------------------------- /memoryleak/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | ../pom.xml 25 | 26 | 27 | 4.0.0 28 | memoryleak 29 | jar 30 | memoryleak 31 | 32 | 33 | 34 | com.github.chrishantha.sample 35 | base 36 | 37 | 38 | 39 | 40 | 41 | 42 | org.apache.maven.plugins 43 | maven-shade-plugin 44 | 45 | 46 | 47 | 48 | -------------------------------------------------------------------------------- /memoryleak/src/main/java/com/github/chrishantha/sample/memoryleak/BadKey.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryleak; 17 | 18 | public class BadKey extends Key { 19 | 20 | public BadKey(long NUMBER, long LENGTH) { 21 | super(NUMBER, LENGTH); 22 | } 23 | 24 | @Override 25 | public boolean equals(Object o) { 26 | return super.equals(o); 27 | } 28 | 29 | } 30 | -------------------------------------------------------------------------------- /memoryleak/src/main/java/com/github/chrishantha/sample/memoryleak/GoodKey.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryleak; 17 | 18 | import java.util.Objects; 19 | 20 | public class GoodKey extends Key { 21 | 22 | public GoodKey(long NUMBER, long LENGTH) { 23 | super(NUMBER, LENGTH); 24 | } 25 | 26 | @Override 27 | public boolean equals(Object o) { 28 | if (this == o) return true; 29 | if (o == null || getClass() != o.getClass()) return false; 30 | Key key = (Key) o; 31 | return Objects.equals(KEY, key.KEY); 32 | } 33 | 34 | } 35 | -------------------------------------------------------------------------------- /memoryleak/src/main/java/com/github/chrishantha/sample/memoryleak/Key.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryleak; 17 | 18 | import java.util.Objects; 19 | 20 | public abstract class Key { 21 | 22 | protected final String KEY; 23 | 24 | public Key(final long NUMBER, final long LENGTH) { 25 | String binaryString = Long.toBinaryString(NUMBER); 26 | StringBuilder keyBuilder = new StringBuilder(); 27 | long limit = LENGTH - binaryString.length(); 28 | for (long i = 0; i < limit; i++) { 29 | keyBuilder.append('0'); 30 | } 31 | keyBuilder.append(binaryString); 32 | KEY = keyBuilder.toString(); 33 | } 34 | 35 | @Override 36 | public final int hashCode() { 37 | return Objects.hash(KEY); 38 | } 39 | 40 | @Override 41 | public final String toString() { 42 | StringBuilder builder = new StringBuilder(); 43 | builder.append(this.getClass().getSimpleName()); 44 | builder.append(" [key="); 45 | builder.append(KEY); 46 | builder.append("]"); 47 | return builder.toString(); 48 | } 49 | } 50 | -------------------------------------------------------------------------------- /memoryleak/src/main/java/com/github/chrishantha/sample/memoryleak/MemoryLeakApplication.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryleak; 17 | 18 | import com.beust.jcommander.Parameter; 19 | import com.github.chrishantha.sample.base.SampleApplication; 20 | 21 | import java.util.HashMap; 22 | import java.util.Map; 23 | 24 | public class MemoryLeakApplication implements SampleApplication { 25 | 26 | private enum KeyType { 27 | BAD, 28 | GOOD 29 | } 30 | 31 | @Parameter(names = "--length", description = "Length of the Key") 32 | private long length = 1024 * 1024; 33 | 34 | @Parameter(names = "--max", description = "Maximum limit to generate keys") 35 | private int max = 100; 36 | 37 | @Parameter(names = "--key-type", description = "Key Type: Good or Bad") 38 | private KeyType keyType = KeyType.BAD; 39 | 40 | @SuppressWarnings("InfiniteLoopStatement") 41 | @Override 42 | public void start() { 43 | Map map = new HashMap<>(); 44 | while (true) { 45 | for (int i = 0; i < max; i++) { 46 | Key key = KeyType.GOOD.equals(keyType) ? new GoodKey(i, length) : new BadKey(i, length); 47 | if (!map.containsKey(key)) { 48 | map.put(key, "Number:" + i); 49 | } 50 | } 51 | } 52 | } 53 | 54 | @Override 55 | public String toString() { 56 | return "MemoryLeakApplication{" + 57 | "length=" + length + 58 | ", max=" + max + 59 | ", keyType=" + keyType + 60 | '}'; 61 | } 62 | } 63 | -------------------------------------------------------------------------------- /memoryleak/src/main/resources/META-INF/services/com.github.chrishantha.sample.base.SampleApplication: -------------------------------------------------------------------------------- 1 | com.github.chrishantha.sample.memoryleak.MemoryLeakApplication -------------------------------------------------------------------------------- /memoryref/README.md: -------------------------------------------------------------------------------- 1 | Sample to a show memory references in a Java Application 2 | ======================================================== 3 | 4 | This sample application creates objects from classes `A`, `B`, `C`, `D`, `E`, `F`, and `G`. 5 | Each of the previously mentioned classes extend to `Base` class, which creates a significantly 6 | large byte array in the constructor. 7 | 8 | Following is the class diagram. 9 | 10 | ![Class Diagram](classes.png "Class Diagram") 11 | 12 | The application is created to demonstrate the references among objects. 13 | 14 | The sample application creates an object from class `A` in the main thread and another object from 15 | class `G` in a daemon thread. 16 | 17 | The instance created from class `A` references the instances created from other classes as shown below. 18 | 19 | ![References](references.png "References") 20 | 21 | Following is the object diagram showing the object references after the application is started. 22 | 23 | ![Object Diagram](objects.png "Object Diagram") 24 | 25 | ### How to run 26 | 27 | Use the following command to run the application. The application creates an object from class `A` in 28 | the main thread and another object from class `G` in a daemon thread. After that the application will 29 | wait for a keyboard input. 30 | 31 | ```bash 32 | java -Xmn1g -Xmx2g -XX:+PrintGC -XX:+PrintGCDetails -XX:+PrintGCDateStamps -javaagent:target/memoryref.jar -jar target/memoryref.jar 33 | ``` 34 | 35 | ### Looking at object references using a Heap Dump. 36 | 37 | A heap dump can be obtained from following command to look at the object references in heap memory. 38 | 39 | ```bash 40 | jmap -dump:file=target/heap.hprof $(pgrep -f memoryref) 41 | ``` 42 | 43 | Use [Eclipse Memory Analyzer Tool (MAT)](https://www.eclipse.org/mat/) to analyze the heap dump. 44 | 45 | For more information, read following story based on this sample application. 46 | 47 | [Basic concepts of Java heap dump analysis with Eclipse Memory Analyzer Tool (MAT)](https://medium.com/@chrishantha/basic-concepts-of-java-heap-dump-analysis-with-mat-e3615fd79eb) 48 | 49 | Note: Images were created using [draw.io](https://www.draw.io/). 50 | -------------------------------------------------------------------------------- /memoryref/classes.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/chrishantha/sample-java-programs/f688758a2df95f3d8dc59c296a473d8b52309f30/memoryref/classes.png -------------------------------------------------------------------------------- /memoryref/objects.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/chrishantha/sample-java-programs/f688758a2df95f3d8dc59c296a473d8b52309f30/memoryref/objects.png -------------------------------------------------------------------------------- /memoryref/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | ../pom.xml 25 | 26 | 27 | 4.0.0 28 | memoryref 29 | jar 30 | memoryref 31 | 32 | 33 | 34 | com.github.chrishantha.sample 35 | base 36 | 37 | 38 | 39 | 40 | 41 | 42 | org.apache.maven.plugins 43 | maven-shade-plugin 44 | 45 | 46 | 47 | 48 | 49 | 50 | com.github.chrishantha.sample.memoryref.JavaAgent 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | -------------------------------------------------------------------------------- /memoryref/references.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/chrishantha/sample-java-programs/f688758a2df95f3d8dc59c296a473d8b52309f30/memoryref/references.png -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/A.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | public class A extends Base { 19 | 20 | final B b; 21 | final C c; 22 | 23 | A() { 24 | b = new B(); 25 | c = new C(b); 26 | } 27 | 28 | @Override 29 | public long getSize() { 30 | return super.getSize() + b.getSize() + c.getSize(); 31 | } 32 | } -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/B.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | public class B extends Base { 19 | 20 | final D d; 21 | final E e; 22 | 23 | B() { 24 | d = new D(); 25 | e = new E(); 26 | } 27 | 28 | @Override 29 | public long getSize() { 30 | return super.getSize() + d.getSize() + e.getSize(); 31 | } 32 | } 33 | -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/Base.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | import java.util.Random; 19 | 20 | public abstract class Base { 21 | 22 | private final byte[] bytes; 23 | private static final Random random = new Random(); 24 | 25 | Base() { 26 | bytes = new byte[(10 * (1 + random.nextInt(10))) * 1024 * 1024]; 27 | } 28 | 29 | public long getSize() { 30 | return JavaAgent.getObjectSize(this) + JavaAgent.getObjectSize(bytes); 31 | } 32 | } 33 | -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/C.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | public class C extends Base { 19 | 20 | final E e; 21 | final F f; 22 | 23 | C(B b) { 24 | this.e = b.e; 25 | f = new F(); 26 | } 27 | 28 | @Override 29 | public long getSize() { 30 | return super.getSize() + f.getSize(); 31 | } 32 | 33 | } 34 | -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/D.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | public class D extends Base { 19 | 20 | } 21 | -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/E.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | public class E extends Base { 19 | 20 | } 21 | -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/F.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | public class F extends Base { 19 | 20 | } 21 | -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/G.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | public class G extends Base { 19 | 20 | } 21 | -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/JavaAgent.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | import java.lang.instrument.Instrumentation; 19 | 20 | public class JavaAgent { 21 | private static volatile Instrumentation instrumentation; 22 | 23 | public static void premain(final String agentArgs, final Instrumentation instrumentation) { 24 | JavaAgent.instrumentation = instrumentation; 25 | } 26 | 27 | public static long getObjectSize(final Object object) { 28 | if (instrumentation == null) { 29 | return -1L; 30 | } 31 | return instrumentation.getObjectSize(object); 32 | } 33 | } -------------------------------------------------------------------------------- /memoryref/src/main/java/com/github/chrishantha/sample/memoryref/MemoryRefApplication.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2019 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.memoryref; 17 | 18 | import com.github.chrishantha.sample.base.SampleApplication; 19 | 20 | import java.io.IOException; 21 | 22 | public class MemoryRefApplication implements SampleApplication { 23 | 24 | @Override 25 | public void start() { 26 | A a = new A(); 27 | long size = a.getSize(); 28 | System.out.format("The retained heap size of object A is %d bytes (~%d MiB).%n", 29 | size, (size / (1024 * 1024))); 30 | long objectSize = JavaAgent.getObjectSize(a); 31 | if (objectSize > 0) { 32 | System.out.format("The shallow heap size of object A is %d bytes.%n", objectSize); 33 | } else { 34 | System.out.println("WARNING: Java Agent is not initialized properly."); 35 | } 36 | Thread backgroundThread = new Thread() { 37 | 38 | private long getSize() { 39 | G g = new G(); 40 | return g.getSize(); 41 | } 42 | 43 | @Override 44 | public void run() { 45 | long size = getSize(); 46 | System.out.format("The size of object allocated within the background thread was %d bytes (~%d MiB).%n", 47 | size, (size / (1024 * 1024))); 48 | try { 49 | Thread.sleep(Long.MAX_VALUE); 50 | } catch (InterruptedException e) { 51 | e.printStackTrace(); 52 | } 53 | } 54 | }; 55 | backgroundThread.setName("Background Thread"); 56 | backgroundThread.setDaemon(true); 57 | backgroundThread.start(); 58 | try { 59 | System.out.println("Press Enter to exit."); 60 | System.in.read(); 61 | } catch (IOException e) { 62 | e.printStackTrace(); 63 | } 64 | } 65 | 66 | @Override 67 | public String toString() { 68 | return "MemoryRefApplication"; 69 | } 70 | } 71 | -------------------------------------------------------------------------------- /memoryref/src/main/resources/META-INF/services/com.github.chrishantha.sample.base.SampleApplication: -------------------------------------------------------------------------------- 1 | com.github.chrishantha.sample.memoryref.MemoryRefApplication -------------------------------------------------------------------------------- /pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 4.0.0 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | pom 25 | 26 | Java Samples 27 | Java Sample Code to be used in examples (in blog, etc) 28 | 2015 29 | 30 | 31 | 32 | The Apache Software License, Version 2.0 33 | http://www.apache.org/licenses/LICENSE-2.0.txt 34 | repo 35 | 36 | 37 | 38 | 39 | https://github.com/chrishantha/sample-java-programs.git 40 | scm:git:https://github.com/chrishantha/sample-java-programs.git 41 | scm:git:https://github.com/chrishantha/sample-java-programs.git 42 | HEAD 43 | 44 | 45 | 46 | base 47 | highcpu 48 | hotmethods 49 | latencies 50 | allocations 51 | deadlock 52 | memoryleak 53 | threadleak 54 | memoryref 55 | 56 | 57 | 58 | 59 | 60 | com.beust 61 | jcommander 62 | ${jcommander.version} 63 | 64 | 65 | com.github.chrishantha.sample 66 | base 67 | ${samples.version} 68 | 69 | 70 | org.hdrhistogram 71 | HdrHistogram 72 | ${hdrhistogram.version} 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | org.apache.maven.plugins 82 | maven-shade-plugin 83 | 3.5.2 84 | 85 | 86 | 87 | shade 88 | 89 | 90 | 91 | 93 | com.github.chrishantha.sample.base.App 94 | 95 | 96 | 97 | 98 | 99 | 100 | 101 | 102 | 103 | 104 | org.apache.maven.plugins 105 | maven-compiler-plugin 106 | 3.13.0 107 | 108 | ${javac.target} 109 | ${javac.target} 110 | ${javac.target} 111 | 112 | 113 | 114 | org.apache.maven.plugins 115 | maven-enforcer-plugin 116 | 3.4.1 117 | 118 | 119 | enforce-maven 120 | 121 | enforce 122 | 123 | 124 | 125 | 126 | 3.9 127 | 128 | 129 | 130 | 131 | 132 | 133 | 134 | ${project.name} 135 | 136 | 137 | 138 | 139 | pedantic 140 | 141 | 142 | 143 | org.apache.rat 144 | apache-rat-plugin 145 | 0.16.1 146 | 147 | 148 | **/README.md 149 | .travis.yml 150 | **/*.svg 151 | dependency-reduced-pom.xml 152 | **/com.github.chrishantha.sample.base.SampleApplication 153 | 154 | 155 | 156 | 157 | verify 158 | 159 | check 160 | 161 | 162 | 163 | 164 | 165 | 166 | 167 | 168 | 169 | 170 | UTF-8 171 | 1.8 172 | 0.0.2-SNAPSHOT 173 | 1.82 174 | 2.1.12 175 | 176 | 177 | -------------------------------------------------------------------------------- /threadleak/README.md: -------------------------------------------------------------------------------- 1 | Sample to show thread leaks in a Java Application 2 | ================================================= 3 | 4 | This sample application implements merge sort algorithm using multiple threads. 5 | 6 | The algorithm for parallel merge sort was taken from the [Merge Sort example available online from the University 7 | of Washington](https://courses.cs.washington.edu/courses/cse373/13wi/lectures/03-13/MergeSort.java) 8 | 9 | The original example uses threads directly. This sample application uses an `ExecutorService` to run threads. 10 | 11 | This application runs continuously and prints an interval summary statistics of algorithm run time for multiple random 12 | number arrays. The application will also print final summary statistics of algorithm run time at the program exit. 13 | 14 | ### How to run 15 | 16 | The application will throw Out of Memory error after some time when you run following command 17 | 18 | `java -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints 19 | -XX:+UnlockCommercialFeatures -XX:+FlightRecorder 20 | -XX:StartFlightRecording=settings=profile,duration=2m,name=ThreadLeak,filename=threadleak.jfr 21 | -XX:FlightRecorderOptions=loglevel=info 22 | -jar target/threadleak.jar` 23 | 24 | ### Analyzing Java Flight Recording 25 | 26 | In Threads -> Overview tab, you should see thread count is increasing steadily. 27 | 28 | ### How to fix the Thread Leak 29 | 30 | Run the application with `--stop-leakage` parameter, which will use a single `ExecutorService` throughout the 31 | application. 32 | -------------------------------------------------------------------------------- /threadleak/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 17 | 19 | 20 | 21 | com.github.chrishantha.sample 22 | java-samples 23 | 0.0.2-SNAPSHOT 24 | ../pom.xml 25 | 26 | 27 | 4.0.0 28 | threadleak 29 | jar 30 | threadleak 31 | 32 | 33 | 34 | com.github.chrishantha.sample 35 | base 36 | 37 | 38 | org.hdrhistogram 39 | HdrHistogram 40 | 41 | 42 | 43 | 44 | 45 | 46 | org.apache.maven.plugins 47 | maven-shade-plugin 48 | 49 | 50 | 51 | 52 | -------------------------------------------------------------------------------- /threadleak/src/main/java/com/github/chrishantha/sample/threadleak/ThreadLeakApplication.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 M. Isuru Tharanga Chrishantha Perera 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.github.chrishantha.sample.threadleak; 17 | 18 | import com.beust.jcommander.Parameter; 19 | import com.github.chrishantha.sample.base.SampleApplication; 20 | import com.github.chrishantha.sample.base.Utils; 21 | import org.HdrHistogram.Histogram; 22 | import org.HdrHistogram.Recorder; 23 | 24 | import java.lang.management.ManagementFactory; 25 | import java.lang.management.ThreadMXBean; 26 | import java.time.LocalDateTime; 27 | import java.time.format.DateTimeFormatter; 28 | import java.util.Arrays; 29 | import java.util.Map; 30 | import java.util.Random; 31 | import java.util.Timer; 32 | import java.util.TimerTask; 33 | import java.util.concurrent.ConcurrentSkipListMap; 34 | import java.util.concurrent.ExecutorService; 35 | import java.util.concurrent.Executors; 36 | import java.util.concurrent.Future; 37 | 38 | @SuppressWarnings("FieldCanBeLocal") 39 | public class ThreadLeakApplication implements SampleApplication { 40 | 41 | // Random number generator 42 | private static final Random random = new Random(); 43 | 44 | // Get the Thread MXBean. 45 | private final static ThreadMXBean threadMXBean = ManagementFactory.getThreadMXBean(); 46 | 47 | // Formatter to print current time 48 | private final static DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); 49 | 50 | @Parameter(names = "--threads", description = "Number of threads to be used for merge sorting algorithm.") 51 | private int threads = Runtime.getRuntime().availableProcessors(); 52 | 53 | @Parameter(names = "--initial-length", description = "Initial length of random number array to sort.") 54 | private int length = 1_000; 55 | 56 | @Parameter(names = "--runs", description = "How many times to grow the array by 2") 57 | private int runs = 16; 58 | 59 | @Parameter(names = "--bound", description = "Upper bound of values in array.") 60 | private int bound = 1_000_000; 61 | 62 | @Parameter(names = "--delay", description = "Initial delay in seconds to print statistics. Default: 10 seconds.") 63 | private int delay = 10; 64 | 65 | @Parameter(names = "--period", description = "Period in seconds to print statistics. Default: 30 seconds.") 66 | private int period = 30; 67 | 68 | @Parameter(names = "--stop-leakage", description = "Stop leaking threads.", arity = 0) 69 | private boolean stopLeakage = false; 70 | 71 | @Parameter(names = "--exit-timeout", description = "Exit timeout in seconds " + 72 | "(Default 2 minutes. Use 0 to run forever)") 73 | private int exitTimeoutInSeconds = 2 * 60; 74 | 75 | private volatile ExecutorService executorService; 76 | 77 | @SuppressWarnings("InfiniteLoopStatement") 78 | @Override 79 | public void start() { 80 | System.out.println("Starting Application..."); 81 | Utils.exitApplication(exitTimeoutInSeconds); 82 | 83 | // Map of stats for each array size used for merge sorting 84 | final Map recorderMap = new ConcurrentSkipListMap<>(); 85 | 86 | // Schedule the printing of statistics 87 | final Timer timer = new Timer(); 88 | timer.schedule(new TimerTask() { 89 | public void run() { 90 | printHeader("Interval"); 91 | for (Map.Entry entry : recorderMap.entrySet()) { 92 | StatsRecorder statsRecorder = entry.getValue(); 93 | Histogram histogram = statsRecorder.recorder.getIntervalHistogram(); 94 | statsRecorder.accumulatedHistogram.add(histogram); 95 | printRow(entry.getKey(), histogram); 96 | } 97 | } 98 | }, delay * 1000, period * 1000); 99 | 100 | // Print statistics at exit 101 | Runtime.getRuntime().addShutdownHook(new Thread(() -> { 102 | printHeader("Final"); 103 | for (Map.Entry entry : recorderMap.entrySet()) { 104 | StatsRecorder statsRecorder = entry.getValue(); 105 | Histogram histogram = statsRecorder.accumulatedHistogram; 106 | printRow(entry.getKey(), histogram); 107 | } 108 | })); 109 | 110 | // Run continuously. 111 | while (true) { 112 | // Initial array length 113 | int arrayLength = length; 114 | for (int i = 1; i <= runs; i++) { 115 | int[] numbers = createRandomArray(arrayLength); 116 | 117 | // run the algorithm and measure how long it takes 118 | long startTime = System.nanoTime(); 119 | parallelMergeSort(numbers); 120 | long endTime = System.nanoTime(); 121 | StatsRecorder statsRecorder = recorderMap.compute(arrayLength, (integer, existingRecorder) -> { 122 | if (existingRecorder != null) { 123 | return existingRecorder; 124 | } else { 125 | return new StatsRecorder(); 126 | } 127 | }); 128 | statsRecorder.recorder.recordValue(endTime - startTime); 129 | 130 | if (!isSorted(numbers)) { 131 | throw new RuntimeException("Array is not sorted: " + Arrays.toString(numbers)); 132 | } 133 | 134 | arrayLength *= 2; // double size of array for next time 135 | } 136 | } 137 | } 138 | 139 | private static class StatsRecorder { 140 | // HdrHistogram recorder to record algorithm run time. 141 | Recorder recorder = new Recorder(2); 142 | // Accumulated values 143 | Histogram accumulatedHistogram = new Histogram(2); 144 | } 145 | 146 | private void printHeader(String summary) { 147 | System.out.printf("Time: %20s, Summary: %8s, Thread Count: %3d, Unit: milliseconds (ms)\n", 148 | LocalDateTime.now().format(formatter), 149 | summary, 150 | threadMXBean.getThreadCount()); 151 | System.out.printf("%8s, %7s, " + 152 | "%7s, %7s, %7s, " + 153 | "%7s, %7s, " + 154 | "%7s, %7s, %7s, %7s\n", 155 | "Elements", "Samples", 156 | "Avg", "Min", "Max", 157 | "StdDev", "Median", 158 | "p75", "p98", "p99", "p99.9"); 159 | } 160 | 161 | private void printRow(int elements, Histogram histogram) { 162 | System.out.printf("%8d, %7d," + 163 | " %7.2f, %7.2f, %7.2f," + 164 | " %7.2f, %7.2f, " + 165 | "%7.2f, %7.2f, %7.2f, %7.2f\n", elements, 166 | histogram.getTotalCount(), 167 | histogram.getMean() / 1E6, 168 | histogram.getMinValue() / 1E6, 169 | histogram.getMaxValue() / 1E6, 170 | histogram.getStdDeviation() / 1E6, 171 | histogram.getValueAtPercentile(0.5) / 1E6, 172 | histogram.getValueAtPercentile(0.75) / 1E6, 173 | histogram.getValueAtPercentile(0.98) / 1E6, 174 | histogram.getValueAtPercentile(0.99) / 1E6, 175 | histogram.getValueAtPercentile(0.999) / 1E6); 176 | } 177 | 178 | private ExecutorService getExecutorService() { 179 | if (stopLeakage) { 180 | // Return a single executor service. 181 | if (executorService == null) { 182 | synchronized (this) { 183 | if (executorService == null) { 184 | executorService = Executors.newFixedThreadPool(threads); 185 | } 186 | } 187 | } 188 | return executorService; 189 | } else { 190 | // Always to return a new executor service to leak threads. 191 | return Executors.newFixedThreadPool(threads); 192 | } 193 | } 194 | 195 | /** 196 | * Run parallel merge sort algorithm 197 | * 198 | * @param numbers The numbers to sort. 199 | */ 200 | private void parallelMergeSort(int[] numbers) { 201 | parallelMergeSort(numbers, getExecutorService(), threads); 202 | } 203 | 204 | /** 205 | * This is a recursive method. 206 | * 207 | * @param numbers The numbers to sort. 208 | * @param executorService The {@link ExecutorService} to submit parallel tasks. 209 | * @param threadCount The number of threads to use 210 | */ 211 | private void parallelMergeSort(int[] numbers, ExecutorService executorService, int threadCount) { 212 | if (threadCount <= 1) { 213 | mergeSort(numbers); 214 | } else if (numbers.length >= 2) { 215 | // split array in half 216 | int[] left = Arrays.copyOfRange(numbers, 0, numbers.length / 2); 217 | int[] right = Arrays.copyOfRange(numbers, numbers.length / 2, numbers.length); 218 | Runnable leftSorter = () -> parallelMergeSort(left, executorService, threadCount / 2); 219 | Runnable rightSorter = () -> parallelMergeSort(right, executorService, threadCount / 2); 220 | Future leftResult = executorService.submit(leftSorter); 221 | Future rightResult = executorService.submit(rightSorter); 222 | try { 223 | leftResult.get(); 224 | rightResult.get(); 225 | } catch (Exception e) { 226 | throw new RuntimeException("Unexpected error", e); 227 | } 228 | // merge them back together 229 | merge(left, right, numbers); 230 | } 231 | } 232 | 233 | /** 234 | * Arranges the elements of the given array into sorted order 235 | * using the "merge sort" algorithm, which splits the array in half, 236 | * recursively sorts the halves, then merges the sorted halves. 237 | * It is O(N log N) for all inputs. 238 | * 239 | * @param numbers The numbers to sort. 240 | */ 241 | private void mergeSort(int[] numbers) { 242 | if (numbers.length >= 2) { 243 | // split array in half 244 | int[] left = Arrays.copyOfRange(numbers, 0, numbers.length / 2); 245 | int[] right = Arrays.copyOfRange(numbers, numbers.length / 2, numbers.length); 246 | 247 | // sort the halves 248 | mergeSort(left); 249 | mergeSort(right); 250 | 251 | // merge them back together 252 | merge(left, right, numbers); 253 | } 254 | } 255 | 256 | /** 257 | * Combines the contents of sorted left/right arrays into output array numbers. 258 | * Assumes that left.length + right.length == numbers.length. 259 | * 260 | * @param left The left array. 261 | * @param right The right array. 262 | * @param numbers The output array. 263 | */ 264 | private void merge(int[] left, int[] right, int[] numbers) { 265 | int i1 = 0; 266 | int i2 = 0; 267 | for (int i = 0; i < numbers.length; i++) { 268 | if (i2 >= right.length || (i1 < left.length && left[i1] < right[i2])) { 269 | numbers[i] = left[i1]; 270 | i1++; 271 | } else { 272 | numbers[i] = right[i2]; 273 | i2++; 274 | } 275 | } 276 | } 277 | 278 | /** 279 | * Creates an array of the given length, fills it with random 280 | * non-negative integers, and returns it. 281 | * 282 | * @param length The length of the array. 283 | * @return An array of random numbers with given length. 284 | */ 285 | private int[] createRandomArray(int length) { 286 | int[] numbers = new int[length]; 287 | for (int i = 0; i < numbers.length; i++) { 288 | numbers[i] = random.nextInt(bound); 289 | } 290 | return numbers; 291 | } 292 | 293 | /** 294 | * Returns true if the given array is sorted in ascending order. 295 | * 296 | * @param numbers The number array. 297 | * @return {@code true} if the array is sorted in ascending order, otherwise {@code false} 298 | */ 299 | private boolean isSorted(int[] numbers) { 300 | for (int i = 0; i < numbers.length - 1; i++) { 301 | if (numbers[i] > numbers[i + 1]) { 302 | return false; 303 | } 304 | } 305 | return true; 306 | } 307 | 308 | @Override 309 | public String toString() { 310 | return "ThreadLeakApplication{" + 311 | "threads=" + threads + 312 | ", length=" + length + 313 | ", runs=" + runs + 314 | ", bound=" + bound + 315 | ", delay=" + delay + 316 | ", period=" + period + 317 | ", stopLeakage=" + stopLeakage + 318 | ", exitTimeoutInSeconds=" + exitTimeoutInSeconds + 319 | '}'; 320 | } 321 | } 322 | -------------------------------------------------------------------------------- /threadleak/src/main/resources/META-INF/services/com.github.chrishantha.sample.base.SampleApplication: -------------------------------------------------------------------------------- 1 | com.github.chrishantha.sample.threadleak.ThreadLeakApplication --------------------------------------------------------------------------------