├── .editorconfig ├── .github ├── FUNDING.yml └── dependabot.yml ├── .gitignore ├── Ben.BlockingDetector.sln ├── LICENSE ├── README.md ├── appveyor.yml ├── build.ps1 ├── samples └── mvc │ ├── Controllers │ └── HomeController.cs │ ├── Program.cs │ ├── Startup.cs │ └── mvc.csproj └── src └── Ben.BlockingDetector ├── Ben.BlockingDetector.csproj ├── BlockingDetectionMiddleware.cs ├── BlockingMonitor.cs ├── DetectBlockingSynchronizationContext.cs ├── DiagnosticsLoggerExtensions.cs └── TaskBlockingListener.cs /.editorconfig: -------------------------------------------------------------------------------- 1 | # ASP.NET Core EditorConfig file 2 | 3 | # NOTE: This file focuses on settings Visual Studio 2017 supports natively. For example, VS does not support insert_final_newline. 4 | # We do use it, but it's harder to enforce without a separate VS extension or an editor that supports it. 5 | # See https://docs.microsoft.com/en-us/visualstudio/ide/create-portable-custom-editor-options for more 6 | 7 | # Mark this file as the "root" for everything below this point. This means that editor config files above 8 | # this file will be ignored 9 | root = true 10 | 11 | # Default settings 12 | [*] 13 | indent_style = space 14 | indent_size = 4 15 | charset = utf-8 16 | insert_final_newline = true 17 | 18 | # Unix-only files 19 | [*.sh] 20 | end_of_line = lf 21 | 22 | # 2-space files 23 | [{*.json,*.yml}] 24 | indent_size = 2 25 | 26 | # .NET Code Style Settings 27 | # See https://docs.microsoft.com/en-us/visualstudio/ide/editorconfig-code-style-settings-reference 28 | # REVIEW: Should these be errors? warnings? suggestions? 29 | [{*.cs,*.vb}] 30 | dotnet_sort_system_directives_first = true 31 | 32 | # Don't use 'this.'/'Me.' prefix for anything 33 | dotnet_style_qualification_for_field = false:error 34 | dotnet_style_qualification_for_property = false:error 35 | dotnet_style_qualification_for_method = false:error 36 | dotnet_style_qualification_for_event = false:error 37 | 38 | # Use language keywords over framework type names for type references 39 | # i.e. prefer 'string' over 'String' 40 | dotnet_style_predefined_type_for_locals_parameters_members = true:error 41 | dotnet_style_predefined_type_for_member_access = true:error 42 | 43 | # Prefer object/collection initializers 44 | # This is a suggestion because there are cases where this is necessary 45 | dotnet_style_object_initializer = true:suggestion 46 | dotnet_style_collection_initializer = true:suggestion 47 | 48 | # C# 7: Prefer using named tuple names over '.Item1', '.Item2', etc. 49 | dotnet_style_explicit_tuple_names = true:error 50 | 51 | # Prefer using 'foo ?? bar' over 'foo != null ? foo : bar' 52 | dotnet_style_coalesce_expression = true:error 53 | 54 | # Prefer using '?.' over ternary null checking where possible 55 | dotnet_style_null_propagation = true:error 56 | 57 | # Use 'var' in all cases where it can be used 58 | csharp_style_var_for_built_in_types = true:error 59 | csharp_style_var_when_type_is_apparent = true:error 60 | csharp_style_var_elsewhere = true:error 61 | 62 | # C# 7: Prefer using pattern matching over "if(x is T) { var t = (T)x; }" and "var t = x as T; if(t != null) { ... }" 63 | # REVIEW: Since this is a new C# 7 feature that replaces an existing pattern, I'm making it a suggestion 64 | csharp_style_pattern_matching_over_is_with_cast_check = true:warning 65 | csharp_style_pattern_matching_over_as_with_null_check = true:warning 66 | 67 | # C# 7: Prefer using 'out var' where possible 68 | # REVIEW: Since this is a new C# 7 feature that replaces an existing pattern, I'm making it a suggestion 69 | csharp_style_inlined_variable_declaration = true:error 70 | 71 | # C# 7: Use throw expressions when null-checking 72 | # @davidfowl hates them :) 73 | csharp_style_throw_expression = false:error 74 | 75 | # Prefer using "func?.Invoke(args)" over "if(func != null) { func(args); }" 76 | # REVIEW: Maybe an error? 77 | csharp_style_conditional_delegate_call = true:error 78 | 79 | # Newline settings 80 | # Unsure where docs are. Got these from https://github.com/dotnet/roslyn/blob/master/.editorconfig 81 | csharp_new_line_before_open_brace = all 82 | csharp_new_line_before_else = true 83 | csharp_new_line_before_catch = true 84 | csharp_new_line_before_finally = true 85 | csharp_new_line_before_members_in_object_initializers = true 86 | csharp_new_line_before_members_in_anonymous_types = true 87 | 88 | # Prefer expression-bodied methods, constructors, operators, etc. 89 | csharp_style_expression_bodied_methods = true:suggestion 90 | csharp_style_expression_bodied_constructors = true:suggestion 91 | csharp_style_expression_bodied_operators = true:suggestion 92 | csharp_style_expression_bodied_properties = true:suggestion 93 | csharp_style_expression_bodied_indexers = true:suggestion 94 | csharp_style_expression_bodied_accessors = true:suggestion -------------------------------------------------------------------------------- /.github/FUNDING.yml: -------------------------------------------------------------------------------- 1 | # These are supported funding model platforms 2 | 3 | github: [benaadams] 4 | -------------------------------------------------------------------------------- /.github/dependabot.yml: -------------------------------------------------------------------------------- 1 | # To get started with Dependabot version updates, you'll need to specify which 2 | # package ecosystems to update and where the package manifests are located. 3 | # Please see the documentation for all configuration options: 4 | # https://help.github.com/github/administering-a-repository/configuration-options-for-dependency-updates 5 | 6 | version: 2 7 | updates: 8 | - package-ecosystem: "nuget" # See documentation for possible values 9 | directory: "/" # Location of package manifests 10 | schedule: 11 | interval: "daily" 12 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | ## Ignore Visual Studio temporary files, build results, and 2 | ## files generated by popular Visual Studio add-ons. 3 | ## 4 | ## Get latest from https://github.com/github/gitignore/blob/master/VisualStudio.gitignore 5 | 6 | # User-specific files 7 | *.suo 8 | *.user 9 | *.userosscache 10 | *.sln.docstates 11 | 12 | # User-specific files (MonoDevelop/Xamarin Studio) 13 | *.userprefs 14 | 15 | # Build results 16 | [Dd]ebug/ 17 | [Dd]ebugPublic/ 18 | [Rr]elease/ 19 | [Rr]eleases/ 20 | x64/ 21 | x86/ 22 | bld/ 23 | [Bb]in/ 24 | [Oo]bj/ 25 | [Ll]og/ 26 | 27 | # Visual Studio 2015 cache/options directory 28 | .vs/ 29 | # Uncomment if you have tasks that create the project's static files in wwwroot 30 | #wwwroot/ 31 | 32 | # MSTest test Results 33 | [Tt]est[Rr]esult*/ 34 | [Bb]uild[Ll]og.* 35 | 36 | # NUNIT 37 | *.VisualState.xml 38 | TestResult.xml 39 | 40 | # Build Results of an ATL Project 41 | [Dd]ebugPS/ 42 | [Rr]eleasePS/ 43 | dlldata.c 44 | 45 | # .NET Core 46 | project.lock.json 47 | project.fragment.lock.json 48 | artifacts/ 49 | **/Properties/launchSettings.json 50 | 51 | *_i.c 52 | *_p.c 53 | *_i.h 54 | *.ilk 55 | *.meta 56 | *.obj 57 | *.pch 58 | *.pdb 59 | *.pgc 60 | *.pgd 61 | *.rsp 62 | *.sbr 63 | *.tlb 64 | *.tli 65 | *.tlh 66 | *.tmp 67 | *.tmp_proj 68 | *.log 69 | *.vspscc 70 | *.vssscc 71 | .builds 72 | *.pidb 73 | *.svclog 74 | *.scc 75 | 76 | # Chutzpah Test files 77 | _Chutzpah* 78 | 79 | # Visual C++ cache files 80 | ipch/ 81 | *.aps 82 | *.ncb 83 | *.opendb 84 | *.opensdf 85 | *.sdf 86 | *.cachefile 87 | *.VC.db 88 | *.VC.VC.opendb 89 | 90 | # Visual Studio profiler 91 | *.psess 92 | *.vsp 93 | *.vspx 94 | *.sap 95 | 96 | # TFS 2012 Local Workspace 97 | $tf/ 98 | 99 | # Guidance Automation Toolkit 100 | *.gpState 101 | 102 | # ReSharper is a .NET coding add-in 103 | _ReSharper*/ 104 | *.[Rr]e[Ss]harper 105 | *.DotSettings.user 106 | 107 | # JustCode is a .NET coding add-in 108 | .JustCode 109 | 110 | # TeamCity is a build add-in 111 | _TeamCity* 112 | 113 | # DotCover is a Code Coverage Tool 114 | *.dotCover 115 | 116 | # Visual Studio code coverage results 117 | *.coverage 118 | *.coveragexml 119 | 120 | # NCrunch 121 | _NCrunch_* 122 | .*crunch*.local.xml 123 | nCrunchTemp_* 124 | 125 | # MightyMoose 126 | *.mm.* 127 | AutoTest.Net/ 128 | 129 | # Web workbench (sass) 130 | .sass-cache/ 131 | 132 | # Installshield output folder 133 | [Ee]xpress/ 134 | 135 | # DocProject is a documentation generator add-in 136 | DocProject/buildhelp/ 137 | DocProject/Help/*.HxT 138 | DocProject/Help/*.HxC 139 | DocProject/Help/*.hhc 140 | DocProject/Help/*.hhk 141 | DocProject/Help/*.hhp 142 | DocProject/Help/Html2 143 | DocProject/Help/html 144 | 145 | # Click-Once directory 146 | publish/ 147 | 148 | # Publish Web Output 149 | *.[Pp]ublish.xml 150 | *.azurePubxml 151 | # TODO: Comment the next line if you want to checkin your web deploy settings 152 | # but database connection strings (with potential passwords) will be unencrypted 153 | *.pubxml 154 | *.publishproj 155 | 156 | # Microsoft Azure Web App publish settings. Comment the next line if you want to 157 | # checkin your Azure Web App publish settings, but sensitive information contained 158 | # in these scripts will be unencrypted 159 | PublishScripts/ 160 | 161 | # NuGet Packages 162 | *.nupkg 163 | # The packages folder can be ignored because of Package Restore 164 | **/packages/* 165 | # except build/, which is used as an MSBuild target. 166 | !**/packages/build/ 167 | # Uncomment if necessary however generally it will be regenerated when needed 168 | #!**/packages/repositories.config 169 | # NuGet v3's project.json files produces more ignorable files 170 | *.nuget.props 171 | *.nuget.targets 172 | 173 | # Microsoft Azure Build Output 174 | csx/ 175 | *.build.csdef 176 | 177 | # Microsoft Azure Emulator 178 | ecf/ 179 | rcf/ 180 | 181 | # Windows Store app package directories and files 182 | AppPackages/ 183 | BundleArtifacts/ 184 | Package.StoreAssociation.xml 185 | _pkginfo.txt 186 | 187 | # Visual Studio cache files 188 | # files ending in .cache can be ignored 189 | *.[Cc]ache 190 | # but keep track of directories ending in .cache 191 | !*.[Cc]ache/ 192 | 193 | # Others 194 | ClientBin/ 195 | ~$* 196 | *~ 197 | *.dbmdl 198 | *.dbproj.schemaview 199 | *.jfm 200 | *.pfx 201 | *.publishsettings 202 | orleans.codegen.cs 203 | 204 | # Since there are multiple workflows, uncomment next line to ignore bower_components 205 | # (https://github.com/github/gitignore/pull/1529#issuecomment-104372622) 206 | #bower_components/ 207 | 208 | # RIA/Silverlight projects 209 | Generated_Code/ 210 | 211 | # Backup & report files from converting an old project file 212 | # to a newer Visual Studio version. Backup files are not needed, 213 | # because we have git ;-) 214 | _UpgradeReport_Files/ 215 | Backup*/ 216 | UpgradeLog*.XML 217 | UpgradeLog*.htm 218 | 219 | # SQL Server files 220 | *.mdf 221 | *.ldf 222 | *.ndf 223 | 224 | # Business Intelligence projects 225 | *.rdl.data 226 | *.bim.layout 227 | *.bim_*.settings 228 | 229 | # Microsoft Fakes 230 | FakesAssemblies/ 231 | 232 | # GhostDoc plugin setting file 233 | *.GhostDoc.xml 234 | 235 | # Node.js Tools for Visual Studio 236 | .ntvs_analysis.dat 237 | node_modules/ 238 | 239 | # Typescript v1 declaration files 240 | typings/ 241 | 242 | # Visual Studio 6 build log 243 | *.plg 244 | 245 | # Visual Studio 6 workspace options file 246 | *.opt 247 | 248 | # Visual Studio 6 auto-generated workspace file (contains which files were open etc.) 249 | *.vbw 250 | 251 | # Visual Studio LightSwitch build output 252 | **/*.HTMLClient/GeneratedArtifacts 253 | **/*.DesktopClient/GeneratedArtifacts 254 | **/*.DesktopClient/ModelManifest.xml 255 | **/*.Server/GeneratedArtifacts 256 | **/*.Server/ModelManifest.xml 257 | _Pvt_Extensions 258 | 259 | # Paket dependency manager 260 | .paket/paket.exe 261 | paket-files/ 262 | 263 | # FAKE - F# Make 264 | .fake/ 265 | 266 | # JetBrains Rider 267 | .idea/ 268 | *.sln.iml 269 | 270 | # CodeRush 271 | .cr/ 272 | 273 | # Python Tools for Visual Studio (PTVS) 274 | __pycache__/ 275 | *.pyc 276 | 277 | # Cake - Uncomment if you are using it 278 | # tools/** 279 | # !tools/packages.config 280 | 281 | # Telerik's JustMock configuration file 282 | *.jmconfig 283 | 284 | # BizTalk build output 285 | *.btp.cs 286 | *.btm.cs 287 | *.odx.cs 288 | *.xsd.cs 289 | -------------------------------------------------------------------------------- /Ben.BlockingDetector.sln: -------------------------------------------------------------------------------- 1 |  2 | Microsoft Visual Studio Solution File, Format Version 12.00 3 | # Visual Studio 15 4 | VisualStudioVersion = 15.0.27130.2024 5 | MinimumVisualStudioVersion = 10.0.40219.1 6 | Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Ben.BlockingDetector", "src\Ben.BlockingDetector\Ben.BlockingDetector.csproj", "{B8F88BE6-6B60-4C38-AB2C-4B26716F9037}" 7 | EndProject 8 | Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{C3249EB0-5496-4C83-A6DD-96D3DD5D22D4}" 9 | EndProject 10 | Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "SolutionFiles", "SolutionFiles", "{6E740A85-BFF8-4392-818C-0D19BEDE1643}" 11 | ProjectSection(SolutionItems) = preProject 12 | build.ps1 = build.ps1 13 | README.md = README.md 14 | EndProjectSection 15 | EndProject 16 | Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "samples", "samples", "{101738FB-998A-4278-97C0-A1F1B13200C8}" 17 | EndProject 18 | Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "mvc", "samples\mvc\mvc.csproj", "{7502899E-C210-4469-AA64-F7D61A43353B}" 19 | EndProject 20 | Global 21 | GlobalSection(SolutionConfigurationPlatforms) = preSolution 22 | Debug|Any CPU = Debug|Any CPU 23 | Release|Any CPU = Release|Any CPU 24 | EndGlobalSection 25 | GlobalSection(ProjectConfigurationPlatforms) = postSolution 26 | {B8F88BE6-6B60-4C38-AB2C-4B26716F9037}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 27 | {B8F88BE6-6B60-4C38-AB2C-4B26716F9037}.Debug|Any CPU.Build.0 = Debug|Any CPU 28 | {B8F88BE6-6B60-4C38-AB2C-4B26716F9037}.Release|Any CPU.ActiveCfg = Release|Any CPU 29 | {B8F88BE6-6B60-4C38-AB2C-4B26716F9037}.Release|Any CPU.Build.0 = Release|Any CPU 30 | {7502899E-C210-4469-AA64-F7D61A43353B}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 31 | {7502899E-C210-4469-AA64-F7D61A43353B}.Debug|Any CPU.Build.0 = Debug|Any CPU 32 | {7502899E-C210-4469-AA64-F7D61A43353B}.Release|Any CPU.ActiveCfg = Release|Any CPU 33 | {7502899E-C210-4469-AA64-F7D61A43353B}.Release|Any CPU.Build.0 = Release|Any CPU 34 | EndGlobalSection 35 | GlobalSection(SolutionProperties) = preSolution 36 | HideSolutionNode = FALSE 37 | EndGlobalSection 38 | GlobalSection(NestedProjects) = preSolution 39 | {B8F88BE6-6B60-4C38-AB2C-4B26716F9037} = {C3249EB0-5496-4C83-A6DD-96D3DD5D22D4} 40 | {7502899E-C210-4469-AA64-F7D61A43353B} = {101738FB-998A-4278-97C0-A1F1B13200C8} 41 | EndGlobalSection 42 | GlobalSection(ExtensibilityGlobals) = postSolution 43 | SolutionGuid = {9A347552-4B58-4EB3-A66D-6CD470052398} 44 | EndGlobalSection 45 | EndGlobal 46 | -------------------------------------------------------------------------------- /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 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Ben.BlockingDetector 2 | Blocking Detection for ASP.NET Core 3 | 4 | [![NuGet version (Ben.Demystifier)](https://img.shields.io/nuget/v/Ben.BlockingDetector.svg?style=flat-square)](https://www.nuget.org/packages/Ben.BlockingDetector/) 5 | [![Build status](https://ci.appveyor.com/api/projects/status/7xssvgr4coj898cq?svg=true)](https://ci.appveyor.com/project/benaadams/ben-blockingdetector) 6 | 7 | ## Detect Blocking Calls in ASP.NET Core Applications 8 | 9 | Blocking calls can lead to ThreadPool starvation. Outputs a warning to the log when blocking calls are made on the ThreadPool. 10 | 11 | ### Usage 12 | 13 | Add early to your ASP.NET Core pipeline (see: [samples](https://github.com/benaadams/Ben.BlockingDetector/tree/master/samples/mvc)) 14 | 15 | ```csharp 16 | app.UseBlockingDetection(); 17 | ``` 18 | 19 | ### Caveats 20 | 21 | Doesn't detect everything... so its not a panacea; you should actively try to avoid using blocking calls. 22 | 23 | 1. For `async` methods with occurances of **`.ConfigureAwait(false)`**, detection won't alert for blocking `Monitor` calls after occurences in the case where the returned `Task` wasn't already completed 24 | 2. Won't alert for blocking calls that don't block, like on precompleted `Task`s (e.g. a single small `Body.Write`) 25 | 3. Won't alert for blocking that happens in syscalls (e.g. `File.Read(...)`, `Thread.Sleep`) 26 | 27 | Will detect CLR initiated waits `lock`,`ManualResetEventSlim`,`Semaphore{Slim}`,`Task.Wait`,`Task.Result` etc; if they do block. 28 | 29 | ### Example 30 | If you had a method like: 31 | 32 | ```csharp 33 | [HttpGet("/sync-over-async")] 34 | public static int BlockingTask() 35 | { 36 | // Detected blocking 37 | return MethodAsync().Result; 38 | } 39 | 40 | private static async Task MethodAsync() 41 | { 42 | await Task.Delay(1000); 43 | return 5; 44 | } 45 | ``` 46 | 47 | It would output to your log 48 | 49 | ```csharp 50 | warn: Ben.Diagnostics.BlockingMonitor[6] 51 | Blocking method has been invoked and blocked, this can lead to threadpool starvation. 52 | at System.Threading.Tasks.Task.InternalWait(Int32 millisecondsTimeout, CancellationToken cancellationToken) 53 | at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification) 54 | at mvc.HomeController.BlockingTask() <------------------ ** Blocking function ** 55 | at lambda_method(Closure , Object , Object[] ) 56 | at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters) 57 | at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.d__12.MoveNext() 58 | at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.Start[TStateMachine](TStateMachine& stateMachine) 59 | at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync() 60 | at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) 61 | at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.d__10.MoveNext() 62 | ... 63 | at Microsoft.AspNetCore.Hosting.Internal.RequestServicesContainerMiddleware.Invoke(HttpContext httpContext) 64 | at Microsoft.AspNetCore.Hosting.Internal.HostingApplication.ProcessRequestAsync(Context context) 65 | at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.Frame`1.d__2.MoveNext() 66 | at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) 67 | at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c__DisplayClass4_0.b__0() 68 | at Microsoft.AspNetCore.Server.Kestrel.Internal.System.IO.Pipelines.Pipe.<>c.<.cctor>b__67_3(Object o) 69 | at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure.LoggingThreadPool.<>c__DisplayClass6_0.b__0() 70 | at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure.LoggingThreadPool.b__3_0(Object o) 71 | at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) 72 | at System.Threading.ThreadPoolWorkQueue.Dispatch() 73 | ``` 74 | 75 | Also catches held locks 76 | 77 | ```csharp 78 | 120: public Task LockedMethod(HttpContext httpContext) 79 | 121: { 80 | 122: var response = httpContext.Response; 81 | 123: response.StatusCode = 200; 82 | 124: response.ContentType = "text/plain"; 83 | 125: lock (obj) // ********** 84 | 126: { 85 | 127: // locked outside for 1 sec 86 | 128: } 87 | 129: var s = new string('n', 16); 88 | 130: response.ContentLength = s.Length; 89 | 131: return response.WriteAsync(s); 90 | 132: } 91 | ``` 92 | Outputs (with some extra formatting) 93 | ```csharp 94 | warn: Microsoft.AspNetCore.Diagnostics.DetectBlocking[6] 95 | Blocking method has been invoked and blocked, this can lead to threadpool starvation. 96 | at Task AoA.Gaia.Startup.LockedMethod(HttpContext httpContext) 97 | in C:\Work\AoA\src\AoA.Gaia\Startup.cs:line 125 ******** 98 | at IApplicationBuilder Microsoft.AspNetCore.Builder.UseExtensions.Use(IApplicationBuilder app, Func, Task> middleware)+() => { } 99 | .... 100 | at void Microsoft.AspNetCore.Server.Kestrel.Internal.System.IO.Pipelines.Pipe._scheduleContinuation(object o) 101 | at void Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure.LoggingThreadPool.Schedule(Action action, object state)+() => { } 102 | at void Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure.LoggingThreadPool.RunAction()+(object o) => { } 103 | at bool System.Threading.ThreadPoolWorkQueue.Dispatch() 104 | ``` 105 | -------------------------------------------------------------------------------- /appveyor.yml: -------------------------------------------------------------------------------- 1 | image: Visual Studio 2017 2 | 3 | shallow_clone: true 4 | 5 | branches: 6 | only: 7 | - master 8 | 9 | skip_branch_with_pr: true 10 | 11 | skip_tags: true 12 | 13 | skip_commits: 14 | files: 15 | - BUILDING.md 16 | - CONTRIBUTING.md 17 | - ISSUE_TEMPLATE.md 18 | - LICENCE 19 | - README.md 20 | 21 | nuget: 22 | disable_publish_on_pr: true 23 | 24 | build_script: 25 | - ps: .\build.ps1 -target appveyor -buildAssemblyVersion ($env:BuildVersion + $env:APPVEYOR_BUILD_NUMBER) -buildSemanticVersion ($env:BuildSemanticVersion + $env:APPVEYOR_BUILD_NUMBER) 26 | 27 | test: off 28 | 29 | deploy: off 30 | 31 | artifacts: 32 | - path: artifacts/build 33 | - path: artifacts/packages 34 | - path: artifacts/test -------------------------------------------------------------------------------- /build.ps1: -------------------------------------------------------------------------------- 1 | <# 2 | .SYNOPSIS 3 | This is a helper function that runs a scriptblock and checks the PS variable $lastexitcode 4 | to see if an error occcured. If an error is detected then an exception is thrown. 5 | This function allows you to run command-line programs without having to 6 | explicitly check the $lastexitcode variable. 7 | .EXAMPLE 8 | exec { svn info $repository_trunk } "Error executing SVN. Please verify SVN command-line client is installed" 9 | #> 10 | function Exec 11 | { 12 | [CmdletBinding()] 13 | param( 14 | [Parameter(Position=0,Mandatory=1)][scriptblock]$cmd, 15 | [Parameter(Position=1,Mandatory=0)][string]$errorMessage = ($msgs.error_bad_command -f $cmd) 16 | ) 17 | & $cmd 18 | if ($lastexitcode -ne 0) { 19 | throw ("Exec: " + $errorMessage) 20 | } 21 | } 22 | 23 | if(Test-Path .\artifacts) { Remove-Item .\artifacts -Force -Recurse } 24 | 25 | exec { & dotnet restore } 26 | 27 | $revision = @{ $true = $env:APPVEYOR_BUILD_NUMBER; $false = 1 }[$env:APPVEYOR_BUILD_NUMBER -ne $NULL]; 28 | $revision = "{0:D4}" -f [convert]::ToInt32($revision, 10) 29 | 30 | exec { & dotnet pack .\src\Ben.BlockingDetector -c Release -o .\artifacts --version-suffix=$revision } -------------------------------------------------------------------------------- /samples/mvc/Controllers/HomeController.cs: -------------------------------------------------------------------------------- 1 | using System.Threading; 2 | using System.Threading.Tasks; 3 | using Microsoft.AspNetCore.Mvc; 4 | 5 | #pragma warning disable IDE0007 6 | namespace mvc 7 | { 8 | public class HomeController : Controller 9 | { 10 | [HttpGet("/")] 11 | public Task Slower() 12 | { 13 | // Detected blocking in called method 14 | return DoSomethingAsync(); 15 | } 16 | 17 | private async Task DoSomethingAsync() 18 | { 19 | await Task.Delay(1000); 20 | 21 | // Detected blocking 22 | Task.Run (() => { Thread.Sleep(1000); }).Wait(); 23 | } 24 | 25 | [HttpGet("/hello")] 26 | public string Hello() 27 | { 28 | // Not detected: Thread.Sleep happens at OS level 29 | Thread.Sleep(2000); 30 | 31 | return "Hello World"; 32 | } 33 | 34 | [HttpGet("/hello-sync-over-async")] 35 | public string HelloSyncOverAsync() 36 | { 37 | // Detected blocking 38 | Task.Delay(2000).Wait(); 39 | 40 | return "Hello World"; 41 | } 42 | 43 | [HttpGet("/hello-async-over-sync")] 44 | public async Task HelloAsyncOverSync() 45 | { 46 | // Detected blocking in called method 47 | var result = await Task.Run(() => BlockingTask()); 48 | 49 | return $"Hello World {result}"; 50 | } 51 | 52 | private static int BlockingTask() 53 | { 54 | // Detected blocking 55 | return MethodAsync().Result; 56 | } 57 | 58 | private static async Task MethodAsync() 59 | { 60 | await Task.Delay(1000); 61 | return 5; 62 | } 63 | 64 | [HttpGet("/hello-async")] 65 | public async Task HelloAsync() 66 | { 67 | // No blocking :) 68 | await Task.Delay(2000); 69 | 70 | return "Hello World"; 71 | } 72 | 73 | [HttpGet("/hello-async-precompleted")] 74 | public async Task HelloAsyncPrecompleted() 75 | { 76 | Task task = MethodAsync(); 77 | 78 | if (!task.IsCompletedSuccessfully) 79 | { 80 | // Await completes the Task without blocking 81 | await task; 82 | } 83 | 84 | // The task is completed at this point so .Result doesn't trigger blocking 85 | var result = task.Result; 86 | 87 | return $"Hello World {result}"; 88 | } 89 | } 90 | 91 | #pragma warning restore IDE0007 92 | } 93 | -------------------------------------------------------------------------------- /samples/mvc/Program.cs: -------------------------------------------------------------------------------- 1 | using Microsoft.AspNetCore; 2 | using Microsoft.AspNetCore.Hosting; 3 | 4 | namespace mvc 5 | { 6 | public class Program 7 | { 8 | public static void Main(string[] args) 9 | { 10 | BuildWebHost(args).Run(); 11 | } 12 | 13 | public static IWebHost BuildWebHost(string[] args) => 14 | WebHost.CreateDefaultBuilder(args) 15 | .UseStartup() 16 | .Build(); 17 | } 18 | } 19 | -------------------------------------------------------------------------------- /samples/mvc/Startup.cs: -------------------------------------------------------------------------------- 1 | using Ben.Diagnostics; 2 | using Microsoft.AspNetCore.Builder; 3 | using Microsoft.AspNetCore.Hosting; 4 | using Microsoft.Extensions.DependencyInjection; 5 | 6 | namespace mvc 7 | { 8 | public class Startup 9 | { 10 | public void ConfigureServices(IServiceCollection services) 11 | { 12 | services.AddMvc(); 13 | } 14 | 15 | public void Configure(IApplicationBuilder app, IHostingEnvironment env) 16 | { 17 | // Add blocking detector at start of Configure 18 | app.UseBlockingDetection(); 19 | 20 | if (env.IsDevelopment()) 21 | { 22 | app.UseDeveloperExceptionPage(); 23 | } 24 | 25 | app.UseMvc(); 26 | } 27 | } 28 | } 29 | -------------------------------------------------------------------------------- /samples/mvc/mvc.csproj: -------------------------------------------------------------------------------- 1 |  2 | 3 | 4 | netcoreapp2.1 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | -------------------------------------------------------------------------------- /src/Ben.BlockingDetector/Ben.BlockingDetector.csproj: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | Ben Core 6 | Ben.BlockingDetector 7 | Blocking Detection for ASP.NET Core 8 | 9 | ben_a_adams 10 | https://github.com/benaadams/Ben.BlockingDetector 11 | https://github.com/benaadams/Ben.BlockingDetector 12 | https://github.com/benaadams/Ben.BlockingDetector/blob/master/LICENSE 13 | 14 | netstandard2.0;netcoreapp3.1;net5.0 15 | Ben.Diagnostics 16 | 17 | git 18 | true 19 | true 20 | 0.0.4 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | -------------------------------------------------------------------------------- /src/Ben.BlockingDetector/BlockingDetectionMiddleware.cs: -------------------------------------------------------------------------------- 1 | using System.Threading; 2 | using System.Threading.Tasks; 3 | using Microsoft.AspNetCore.Builder; 4 | using Microsoft.AspNetCore.Hosting; 5 | using Microsoft.AspNetCore.Http; 6 | using Microsoft.Extensions.Logging; 7 | 8 | namespace Ben.Diagnostics 9 | { 10 | public class BlockingDetectionMiddleware 11 | { 12 | private readonly ILoggerFactory _loggerFactory; 13 | private readonly RequestDelegate _next; 14 | 15 | private readonly BlockingMonitor _monitor; 16 | private readonly DetectBlockingSynchronizationContext _detectBlockingSyncCtx; 17 | private readonly TaskBlockingListener _listener; 18 | 19 | public BlockingDetectionMiddleware(RequestDelegate next, ILoggerFactory loggerFactory) 20 | { 21 | _next = next; 22 | _loggerFactory = loggerFactory; 23 | // Detect blocking 24 | _monitor = new BlockingMonitor(loggerFactory); 25 | _detectBlockingSyncCtx = new DetectBlockingSynchronizationContext(_monitor); 26 | _listener = new TaskBlockingListener(_monitor); 27 | } 28 | 29 | public async Task Invoke(HttpContext httpContext) 30 | { 31 | var syncCtx = SynchronizationContext.Current; 32 | SynchronizationContext.SetSynchronizationContext(syncCtx == null ? _detectBlockingSyncCtx : new DetectBlockingSynchronizationContext(_monitor, syncCtx)); 33 | 34 | try 35 | { 36 | await _next(httpContext); 37 | } 38 | 39 | finally 40 | { 41 | SynchronizationContext.SetSynchronizationContext(syncCtx); 42 | } 43 | } 44 | } 45 | 46 | public static class BlockingDetectionMiddlewareExtensions 47 | { 48 | public static IApplicationBuilder UseBlockingDetection(this IApplicationBuilder builder) 49 | { 50 | return builder.UseMiddleware(); 51 | } 52 | } 53 | } 54 | -------------------------------------------------------------------------------- /src/Ben.BlockingDetector/BlockingMonitor.cs: -------------------------------------------------------------------------------- 1 | using System; 2 | using System.Diagnostics; 3 | using System.Threading; 4 | using Microsoft.Extensions.Logging; 5 | 6 | namespace Ben.Diagnostics 7 | { 8 | internal class BlockingMonitor 9 | { 10 | [ThreadStatic] 11 | private static int t_recursionCount; 12 | 13 | private readonly ILogger _logger; 14 | 15 | public BlockingMonitor(ILoggerFactory loggerFactory) 16 | { 17 | _logger = loggerFactory.CreateLogger(); 18 | } 19 | 20 | 21 | public void BlockingStart(DectectionSource dectectionSource) 22 | { 23 | if (!Thread.CurrentThread.IsThreadPoolThread) 24 | { 25 | return; 26 | } 27 | 28 | t_recursionCount++; 29 | 30 | try 31 | { 32 | if (t_recursionCount == 1) 33 | { 34 | _logger.BlockingMethodCalled( 35 | new StackTrace(dectectionSource == DectectionSource.SynchronizationContext ? 3 : 6)); 36 | } 37 | } 38 | catch 39 | { 40 | } 41 | } 42 | 43 | public void BlockingEnd() 44 | { 45 | if (!Thread.CurrentThread.IsThreadPoolThread) 46 | { 47 | return; 48 | } 49 | 50 | t_recursionCount--; 51 | } 52 | } 53 | 54 | public enum DectectionSource 55 | { 56 | SynchronizationContext, 57 | EventListener 58 | } 59 | } 60 | -------------------------------------------------------------------------------- /src/Ben.BlockingDetector/DetectBlockingSynchronizationContext.cs: -------------------------------------------------------------------------------- 1 | using System; 2 | using System.Threading; 3 | 4 | namespace Ben.Diagnostics 5 | { 6 | // Tips of the Toub 7 | internal sealed class DetectBlockingSynchronizationContext : SynchronizationContext 8 | { 9 | private readonly BlockingMonitor _monitor; 10 | private readonly SynchronizationContext _syncCtx; 11 | 12 | public DetectBlockingSynchronizationContext(BlockingMonitor monitor) 13 | { 14 | _monitor = monitor; 15 | 16 | SetWaitNotificationRequired(); 17 | } 18 | 19 | public DetectBlockingSynchronizationContext(BlockingMonitor monitor, SynchronizationContext syncCtx) : this(monitor) 20 | { 21 | _syncCtx = syncCtx; 22 | } 23 | 24 | public override int Wait(IntPtr[] waitHandles, bool waitAll, int millisecondsTimeout) 25 | { 26 | if (millisecondsTimeout == 0) 27 | { 28 | return WaitInternal(waitHandles, waitAll, millisecondsTimeout); 29 | } 30 | else 31 | { 32 | _monitor.BlockingStart(DectectionSource.SynchronizationContext); 33 | 34 | try 35 | { 36 | return WaitInternal(waitHandles, waitAll, millisecondsTimeout); 37 | } 38 | finally 39 | { 40 | _monitor.BlockingEnd(); 41 | } 42 | } 43 | } 44 | 45 | private int WaitInternal(IntPtr[] waitHandles, bool waitAll, int millisecondsTimeout) 46 | { 47 | if (_syncCtx != null) 48 | { 49 | return _syncCtx.Wait(waitHandles, waitAll, millisecondsTimeout); 50 | } 51 | else 52 | { 53 | return base.Wait(waitHandles, waitAll, millisecondsTimeout); 54 | } 55 | } 56 | } 57 | } 58 | -------------------------------------------------------------------------------- /src/Ben.BlockingDetector/DiagnosticsLoggerExtensions.cs: -------------------------------------------------------------------------------- 1 | using System; 2 | using System.Diagnostics; 3 | using Microsoft.Extensions.Logging; 4 | 5 | namespace Ben.Diagnostics 6 | { 7 | internal static class DiagnosticsLoggerExtensions 8 | { 9 | // BlockingDetection 10 | private static readonly Action s_blockingMethodCalled = 11 | LoggerMessage.Define(LogLevel.Warning, 12 | new EventId(6, "BlockingMethodCalled"), 13 | "Blocking method has been invoked and blocked, this can lead to threadpool starvation." + Environment.NewLine + "{stackTrace}"); 14 | 15 | public static void BlockingMethodCalled(this ILogger logger, StackTrace stackTrace) 16 | { 17 | s_blockingMethodCalled(logger, stackTrace, null); 18 | } 19 | } 20 | } 21 | -------------------------------------------------------------------------------- /src/Ben.BlockingDetector/TaskBlockingListener.cs: -------------------------------------------------------------------------------- 1 | using System; 2 | using System.Diagnostics.Tracing; 3 | using System.Threading; 4 | 5 | namespace Ben.Diagnostics 6 | { 7 | // Tips of the Toub 8 | internal sealed class TaskBlockingListener : EventListener 9 | { 10 | private static readonly Guid s_tplGuid = new Guid("2e5dba47-a3d2-4d16-8ee0-6671ffdcd7b5"); 11 | 12 | [ThreadStatic] 13 | private static int t_recursionCount; 14 | 15 | private readonly BlockingMonitor _monitor; 16 | 17 | public TaskBlockingListener(BlockingMonitor monitor) 18 | { 19 | _monitor = monitor; 20 | } 21 | 22 | protected override void OnEventSourceCreated(EventSource eventSource) 23 | { 24 | if (eventSource.Guid == s_tplGuid) 25 | { 26 | // 3 == Task|TaskTransfer 27 | EnableEvents(eventSource, EventLevel.Verbose, (EventKeywords) 3); 28 | } 29 | } 30 | 31 | protected override void OnEventWritten(EventWrittenEventArgs eventData) 32 | { 33 | if (!Thread.CurrentThread.IsThreadPoolThread) 34 | { 35 | return; 36 | } 37 | 38 | if (eventData.EventId == 10 && // TASKWAITBEGIN_ID 39 | eventData.Payload != null && 40 | eventData.Payload.Count > 3 && 41 | eventData.Payload[3] is int value && // Behavior 42 | value == 1) // TaskWaitBehavior.Synchronous 43 | { 44 | t_recursionCount++; 45 | _monitor.BlockingStart(DectectionSource.EventListener); 46 | } 47 | else if (eventData.EventId == 11 // TASKWAITEND_ID 48 | && t_recursionCount > 0) 49 | { 50 | t_recursionCount--; 51 | _monitor.BlockingEnd(); 52 | } 53 | } 54 | } 55 | } 56 | --------------------------------------------------------------------------------