├── .gitignore ├── LICENSE ├── README.md ├── README_zh.md ├── pymysqlpool.py ├── setup.py └── simple-benchmark.py /.gitignore: -------------------------------------------------------------------------------- 1 | __pycache__ 2 | 3 | # Packages 4 | *.egg 5 | *.egg-info 6 | dist 7 | build 8 | eggs 9 | .idea 10 | test.py 11 | *.swp 12 | 13 | venv 14 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # PyMySQL Connection Pool 2 | 3 | [中文文档](https://github.com/jkklee/pymysql-pool/blob/master/README_zh.md) 4 | 5 | A simple but not simple mysql connection pool based on `PyMySQL`. 6 | 7 | ## The problem to solve 8 | While using pymysql with python multithreading, generally we will face the questions: 9 | 1. It can't share a connection created by main thread with all sub-threads. It will result in the following error: 10 | `pymysql.err.InternalError: Packet sequence number wrong - got 0 expected 1` 11 | 2. If we make every sub-thread to create a connection and close it when this sub-thread ends that's workable but obviously lead to high cost on establishing connections with MySQL. 12 | 13 | ## Features 14 | 1. Simple: just use it, there is no extra learning costs. 15 | 2. Performance: almost no extra load compared to the original PyMysql([simple benchmark](https://github.com/jkklee/pymysql-pool#simple-benchmark)). 16 | 3. Flexible: pre_create connection or just create when really need; normal pool size and max pool size for the scalability, it all depends on you. 17 | 4. Thoughtful: `connection lifetime` and `pre_ping` mechanism, in case of borrow a brokend connection from the pool(such as closed by the mysql server due to `wait_timeout` setting). 18 | 19 | ## Basic components 20 | This module contains two classes: 21 | - `Connection` class: this is a subclass of `pymysql.connections.Connection`. It can be used with or without a connection_pool, **It used in the exact same way as pymysql**. The details implementation of connection pool is hiddened (when used with a connection_pool additional actions are needed to maintain the pool). 22 | - `ConnectionPool` class: instance of this class represents the actual connection_pool. 23 | 24 | ## Misc 25 | Using the concept of connection pool, there are also some aspects should be considered except the core features, such as: 26 | 27 | - when getting connection from a pool: we should deal with the **retry_num** and **retry_interval** parameters，in order to give the borrower more chance and don't return the `GetConnectionFromPoolError` error directly. 28 | - when putting connection back to pool: if the queries executed without exceptions, this connection can be putted back to the pool directly; but if **exception** occurred we have to decide whether this connection should be putted back to the pool depending on if it is **reusable** (depends on the exception type). 29 | 30 | Luckily, this module will take care of these complicated details for you automaticly. 31 | 32 | It also allows to create more than one connection_pool (with distinct `ConnectionPool.name` attribute) to be associated with different databases. 33 | 34 | ## Usage example 35 | #### Installation 36 | ``` 37 | pip install pymysql-pool 38 | ``` 39 | 40 | In the example below we're going to see how it works: 41 | 42 | 1. Create a pool with base/normal size is 2 and max size is 3, with pre_create_num=2 means will create 2 connections in the init phase: 43 | ``` 44 | >>> import pymysqlpool 45 | >>> pymysqlpool.logger.setLevel('DEBUG') 46 | >>> config={'host':'xxxx', 'user':'xxx', 'password':'xxx', 'database':'xxx', 'autocommit':True} 47 | 48 | >>> mypool = pymysqlpool.ConnectionPool(size=2, maxsize=3, pre_create_num=2, name='mypool', **config) 49 | 03-08 15:54:50 DEBUG: Create new connection in pool(mypool) 50 | 03-08 15:54:50 DEBUG: Create new connection in pool(mypool) 51 | >>> mypool.total_num 52 | 2 53 | 54 | >>> con1 = mypool.get_connection() 55 | 12-25 21:38:48 DEBUG: Get connection from pool(mypool) 56 | >>> con2 = mypool.get_connection() 57 | 12-25 21:38:51 DEBUG: Get connection from pool(mypool) 58 | >>> mypool.available_num 59 | 0 60 | ``` 61 | 2. Now the pool is empty, and we still borrow a connection from it, with the default parameters of get_connection(), we will see : 62 | ``` 63 | >>> con3=mypool.get_connection() 64 | 03-08 15:57:32 DEBUG: Retry to get connection from pool(mypool) 65 | 03-08 15:57:32 DEBUG: Retry to get connection from pool(mypool) 66 | 03-08 15:57:32 DEBUG: Retry to get connection from pool(mypool) 67 | 03-08 15:57:33 DEBUG: Create new connection in pool(mypool) 68 | ``` 69 | above message show us: although pool is empty, but the max size isn't reached, so after several times retry, a new connection is create(now max size of pool is reached) 70 | 71 | 3. Let's try to get another connection from pool: 72 | 73 | ``` 74 | >>> con4=mypool.get_connection() 75 | 03-08 16:29:43 DEBUG: Retry to get connection from pool(mypool) 76 | 03-08 16:29:43 DEBUG: Retry to get connection from pool(mypool) 77 | 03-08 16:29:43 DEBUG: Retry to get connection from pool(mypool) 78 | Traceback (most recent call last): 79 | File "/Users/kai/github/pymysql-pool/pymysqlpool.py", line 176, in get_connection 80 | conn = self._pool.pop() 81 | IndexError: pop from an empty deque 82 | 83 | ... ... 84 | 85 | pymysqlpool.GetConnectionFromPoolError: can't get connection from pool(mypool), retry_interval=0.1(s) 86 | ``` 87 | we can see that after several times retry, finally raise a exception `GetConnectionFromPoolError` 88 | 89 | 4. Now let's see the connection's behavior while calling close() method or using it with Context Manager Protocol 90 | 91 | ``` 92 | >>> con1.close() 93 | 2017-12-25 21:39:56 DEBUG: Put connection back to pool(mypool) 94 | >>> with con2: 95 | with con2.cursor() as cur: 96 | cur.execute('select 1+1') 97 | 98 | 1 99 | 12-20 22:44:37 DEBUG: Put connection back to pool(mypool) 100 | >>> mypool.total_num 101 | 3 # as we expect 102 | >>> mypool.available_num 103 | 2 # as we expect 104 | We can see that the module maintains the pool appropriately when (and only when) we call the close() method or use the Context Manager Protocol of the connection object. 105 | 106 | ## Simple benchmark 107 | I did a simple benchmark, focusing on the performance impact of the "extra" `get` and `return` operations in this module. 108 | The test logic is in the `simple-benchmark.py`, You can check and do it yourself. 109 | Below is my test(loop 50000 ) 110 | ``` 111 | # 'pymysql-one-conn' is the best performing scenario, native pymysql, and all queries are done within a single connection 112 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-one-conn 50000 113 | total 50000 finish within 6.564s. 114 | 7616.86 queries per second, avg 0.13 ms per query 115 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-one-conn 50000 116 | total 50000 finish within 6.647s. 117 | 7522.31 queries per second, avg 0.13 ms per query 118 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-one-conn 50000 119 | total 50000 finish within 6.558s. 120 | 7623.71 queries per second, avg 0.13 ms per query 121 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-one-conn 50000 122 | total 50000 finish within 6.737s. 123 | 7421.67 queries per second, avg 0.13 ms per query 124 | 125 | # 'pymysql-pool' uses connection pool (as long as the pool is greater than 1, it doesn't matter because the test logic is executed sequentially in a for loop). 126 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-pool 50000 127 | total 50000 finish within 6.999s. 128 | 7143.77 queries per second, avg 0.14 ms per query 129 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-pool 50000 130 | total 50000 finish within 7.066s. 131 | 7076.48 queries per second, avg 0.14 ms per query 132 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-pool 50000 133 | total 50000 finish within 6.999s. 134 | 7143.71 queries per second, avg 0.14 ms per query 135 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-pool 50000 136 | total 50000 finish within 6.968s. 137 | 7175.65 queries per second, avg 0.14 ms per query 138 | ``` 139 | As we can see that one time `get` plus `return` operation only takes about 0.01ms. 140 | 141 | ## Note 142 | 1. We should always use either the `close()` method or `Context Manager Protocol` of the connection object. Otherwise the pool will exhaust soon. 143 | 144 | 2. The `Context Manager Protocol` is preferred. It can achieve an effect similar to the "multiplexing", means the more Fine-Grained use of pool, also do more with less connections. 145 | -------------------------------------------------------------------------------- /README_zh.md: -------------------------------------------------------------------------------- 1 | # PyMySQL 连接池 2 | 3 | [English Doc](https://github.com/jkklee/pymysql-pool/blob/master/README.md) 4 | 5 | 一个用于 Python 的数据库链接池模块，基于 PyMySQL。精心设计、使用简单、定位小而美。 6 | 7 | ## 要解决的问题 8 | 9 | 在 Python 多线程场景下使用 PyMySQL 时，我们通常会面临以下问题: 10 | 11 | 1. 无法在子线程中共享主线程中创建的链接，你可能会遇到这种异常： 12 | `pymysql.err.InternalError: Packet sequence number wrong - got 0 expected 1` 13 | 2. 如果我们让每个子线程创建一个连接，这虽然是可行的，但显然会增加与 MySQL 间创建连接的成本；尤其对于 MySQL 来说，维护每条链接都需要一定的资源，过多的链接或者频繁的创建和销毁链接都会对 MySQL 造成额外的压力。 14 | 15 | ## 特点 16 | 17 | 1. 简单: 没有额外的学习成本。 18 | 2. 性能: 与原生的 PyMysql(简单基准)相比，本模块由于维护连接池而带来的开销非常小。[简单基准测试](https://github.com/jkklee/pymysql-pool/blob/master/README_zh.md#%E5%9F%BA%E5%87%86%E6%B5%8B%E8%AF%95)。 19 | 3. 灵活: 预先创建连接或在真正需要时创建;普通池大小和最大池大小对于可伸缩性，这完全取决于你。 20 | 4. 周到: 包含重试机制，以及`connection lifetime`和`pre_ping`机制--以防从连接池中借用一个已断开的连接(例如，MySQL 服务器由于`wait_timeout`设置而关闭)。 21 | 22 | ## 基本组件 23 | 24 | 该模块有两个类: 25 | 26 | - `Connection` 类: 是`pymysql.connections.Connection`的子类，它同时支持有连接池和无连接池两种使用模式。 **它用起来和 pymysql 完全一样**. 维护连接池的逻辑细节被巧妙的隐藏在了经过覆写过的相关方法中。 27 | - `ConnectionPool` 类: 该类实现了维护连接池的逻辑，创建、获取、返回等方法以及总连接数和可用连接数两个属性。 28 | 29 | ## 其他方面 30 | 31 | 使用连接池，还有其他一些方面需要考虑（可以调校），例如： 32 | 33 | - 当获取链接时: 我们需要考虑下当无法获取链接时的重试机制，本模块提供了**retry_num** 和 **retry_interval** 这俩参数，以便给客户端更多的获取链接的机会，而不是直接返回错误`GetConnectionFromPoolError`。 34 | - 当归还链接时: 如果 sql 语句正常执行，那么该链接归还至连接池自然没什么疑问；但是当遇到异常时呢，我们应该将当前链接直接丢弃吗。考虑到有几种异常只是“上层错误”（如.ProgrammingError，IntegrityError 等），并不是链接本身导致的异常，这样的链接完全可以返回给连接池继续使用。本模块考虑了这种情况，以图尽可能多的复用已有链接，少创建新链接。 35 | - 另外他还提供了`ConnectionPool.name`属性，以便创建多个连接池对象。 36 | 37 | ## 使用示例 38 | 39 | #### 安装 40 | 41 | ``` 42 | pip install pymysql-pool 43 | ``` 44 | 45 | 下面的示例中我们来看看它时如何工作的: 46 | 47 | 1. 创建一个连接池：可容纳两个链接（size 参数），这两个链接是预创建的（pre_create_num 参数）；最大可容纳 3 个链接（maxsize 参数），连接池的对象的名子为`mypool`（name 参数） 48 | 49 | ``` 50 | >>> import pymysqlpool 51 | >>> pymysqlpool.logger.setLevel('DEBUG') 52 | >>> config={'host':'xxxx', 'user':'xxx', 'password':'xxx', 'database':'xxx', 'autocommit':True} 53 | 54 | >>> mypool = pymysqlpool.ConnectionPool(size=2, maxsize=3, pre_create_num=2, name='mypool', **config) 55 | 03-08 15:54:50 DEBUG: Create new connection in pool(mypool) 56 | 03-08 15:54:50 DEBUG: Create new connection in pool(mypool) 57 | 58 | >>> mypool.total_num 59 | 2 60 | 61 | >>> con1 = mypool.get_connection() 62 | 12-25 21:38:48 DEBUG: Get connection from pool(mypool) 63 | >>> con2 = mypool.get_connection() 64 | 12-25 21:38:51 DEBUG: Get connection from pool(mypool) 65 | >>> mypool.available_num 66 | 0 67 | ``` 68 | 69 | 2. 现在池中的两个链接都被借出去，池子已经空了，让我们来看看继续执行`get_connection()`方法会怎样 70 | 71 | ``` 72 | >>> con3=mypool.get_connection() 73 | 03-08 15:57:32 DEBUG: Retry to get connection from pool(mypool) 74 | 03-08 15:57:32 DEBUG: Retry to get connection from pool(mypool) 75 | 03-08 15:57:32 DEBUG: Retry to get connection from pool(mypool) 76 | 03-08 15:57:33 DEBUG: Create new connection in pool(mypool) 77 | ``` 78 | 79 | 上面给我们展示了，虽然连接池已空，但是因为还没到 maxsize 规定的最大连接数，所以在经过 3 次重试后（参数默认值），链接池又创建了第 3 条链接，并将它返回给客户端。现在池子以及达到了容量上限，并且依然是空的。 80 | 81 | 3. 让我们继续尝试从池中获取链接 82 | 83 | ``` 84 | >>> con4=mypool.get_connection() 85 | 03-08 16:29:43 DEBUG: Retry to get connection from pool(mypool) 86 | 03-08 16:29:43 DEBUG: Retry to get connection from pool(mypool) 87 | 03-08 16:29:43 DEBUG: Retry to get connection from pool(mypool) 88 | Traceback (most recent call last): 89 | File "/Users/kai/github/pymysql-pool/pymysqlpool.py", line 176, in get_connection 90 | conn = self._pool.pop() 91 | IndexError: pop from an empty deque 92 | 93 | ... ... 94 | 95 | pymysqlpool.GetConnectionFromPoolError: can't get connection from pool(mypool), due to pool lack. 96 | ``` 97 | 98 | 我们看到经过几次重试后，最终抛出了异常 `GetConnectionFromPoolError`。 99 | 100 | 4. 接来下，让我们看看获取到的链接对象在执行`close()`方法或者使用上下文管理器（with 语句）时如何表现 101 | 102 | ``` 103 | >>> con1.close() 104 | 2017-12-25 21:39:56 DEBUG: Put connection back to pool(mypool) 105 | >>> with con2: 106 | with con2.cursor() as cur: 107 | cur.execute('select 1+1') 108 | 109 | 1 110 | 12-20 22:44:37 DEBUG: Put connection back to pool(mypool) 111 | 112 | >>> mypool.total_num 113 | 3 # 如预期 114 | >>> mypool.available_num 115 | 2 # 如预期 116 | ``` 117 | 118 | 我们看到该模块可以很好的管理连接池的“借出”和“归还”动作。 119 | 120 | ## 基准测试 121 | 122 | 我做了一个简单的基准测试，通过和原生 pymysql 对比，来评估该模块维护连接池所带来的性能方面的开销。 123 | 测试逻辑位于`simple-benchmark.py`，你可以在你的环境下自行测试。 124 | 测试结果（循环 50000 次） 125 | 126 | ``` 127 | # 'pymysql-one-conn' 是直接使用pymysql，只建立一次链接，在该链接内执行所有查询，这可以理解为是所有场景里最好的，性能最高的。 128 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-one-conn 50000 129 | total 50000 finish within 6.564s. 130 | 7616.86 queries per second, avg 0.13 ms per query 131 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-one-conn 50000 132 | total 50000 finish within 6.647s. 133 | 7522.31 queries per second, avg 0.13 ms per query 134 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-one-conn 50000 135 | total 50000 finish within 6.558s. 136 | 7623.71 queries per second, avg 0.13 ms per query 137 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-one-conn 50000 138 | total 50000 finish within 6.737s. 139 | 7421.67 queries per second, avg 0.13 ms per query 140 | 141 | # 'pymysql-pool' 使用连接池（该测试只需创建一个大于1的、预先建立链接的池子即可） 142 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-pool 50000 143 | total 50000 finish within 6.999s. 144 | 7143.77 queries per second, avg 0.14 ms per query 145 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-pool 50000 146 | total 50000 finish within 7.066s. 147 | 7076.48 queries per second, avg 0.14 ms per query 148 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-pool 50000 149 | total 50000 finish within 6.999s. 150 | 7143.71 queries per second, avg 0.14 ms per query 151 | ➜ pymysql-pool ✗ python3 simple-benchmark.py pymysql-pool 50000 152 | total 50000 finish within 6.968s. 153 | 7175.65 queries per second, avg 0.14 ms per query 154 | ``` 155 | 156 | 我们可以看到，该模块维护连接池带来的开销是非常小的，一次`get`和`return`操作，总共只耗费约 0.01 毫秒。 157 | 158 | ## 注意 159 | 160 | 1. 我们一定要确保在不用链接时记得调用 Connection 对象的`close()`方法，否则只借不还，连接池将很快被耗尽。 161 | 162 | 2. 更推荐使用 with 语句（`Context Manager Protocol`），因为它在每次查询后都会自动返回链接，相当于更积极的归还链接，有利于更充分的使用池中的每个链接。 163 | 如果不用 with 语句而手动调用 close()方法来归还链接的话，考虑这么一种情况：借用链接---查询---其他逻辑---再次查询---归还链接，那么在第一次查询完毕到第二次查寻完毕这期间，其他线程时无法获得该链接的，若这期间的逻辑比较耗时，岂不是导致了该链接空置。这也是更推荐用 with 语句的原因。 164 | -------------------------------------------------------------------------------- /pymysqlpool.py: -------------------------------------------------------------------------------- 1 | """ 2 | author: ljk 3 | email: chaoyuemyself@hotmail.com 4 | """ 5 | import pymysql 6 | import warnings 7 | import logging 8 | import functools 9 | import inspect 10 | import time 11 | from collections import deque 12 | 13 | __all__ = ['Connection', 'ConnectionPool', 'ConnectionPoolSingleton', 'logger'] 14 | 15 | warnings.filterwarnings('error', category=pymysql.err.Warning) 16 | 17 | # use logging module for easy debug 18 | 19 | 20 | def _init_logger(level='WARNING'): 21 | logger = logging.getLogger(__name__) 22 | handler = logging.StreamHandler() 23 | handler.setFormatter(logging.Formatter(fmt='%(asctime)s %(levelname)8s: %(message)s', datefmt='%m-%d %H:%M:%S')) 24 | logger.addHandler(handler) 25 | logger.setLevel(level) 26 | return logger 27 | 28 | 29 | logger = _init_logger() 30 | 31 | 32 | class Connection(pymysql.connections.Connection): 33 | """ 34 | Return a connection object with or without connection_pool feature. 35 | 36 | This is all the same with pymysql.connections.Connection instance except that with connection_pool feature: 37 | the __exit__() method additionally put the connection back to it's pool 38 | """ 39 | _pool = None 40 | _reusable_expection = (pymysql.err.ProgrammingError, pymysql.err.IntegrityError, pymysql.err.NotSupportedError) 41 | 42 | def __init__(self, *args, **kwargs): 43 | pymysql.connections.Connection.__init__(self, *args, **kwargs) 44 | self.args = args 45 | self.kwargs = kwargs 46 | # self.cursorclass = Cursor 47 | 48 | def __exit__(self, exc, value, traceback): 49 | """ 50 | Overwrite the __exit__() method of pymysql.connections.Connection 51 | 52 | Base action: on successful exit, commit. On exception, rollback 53 | With pool action: put connection back to pool 54 | """ 55 | if self._pool is not None: 56 | if not exc or exc in self._reusable_expection: 57 | '''reusable connection''' 58 | self._pool._put_connection(self) 59 | else: 60 | '''no reusable connection, close it and create a new one put to the pool''' 61 | self._pool = None 62 | try: 63 | self.close() 64 | logger.debug("Close non-reusable connection in pool(%s) caused by %s", self._pool.name, value) 65 | except Exception: 66 | self._force_close() 67 | else: 68 | pymysql.connections.Connection.__exit__(self, exc, value, traceback) 69 | 70 | def close(self): 71 | """ 72 | Overwrite the close() method of pymysql.connections.Connection 73 | 74 | With pool, put connection back to pool; 75 | Without pool, send the quit message and close the socket 76 | """ 77 | if self._pool is not None: 78 | self._pool._put_connection(self) 79 | else: 80 | pymysql.connections.Connection.close(self) 81 | 82 | def ping(self, reconnect=True): 83 | """ 84 | Overwrite the ping() method of pymysql.connections.Connection 85 | Check if the server is alive. 86 | 87 | :param reconnect: If the connection is closed, reconnect. 88 | :type reconnect: boolean 89 | :raise Error: If the connection is closed and reconnect=False. 90 | """ 91 | if self._sock is None: 92 | if reconnect: 93 | self.connect() 94 | reconnect = False 95 | else: 96 | raise pymysql.err.Error("Already closed") 97 | try: 98 | self._execute_command(pymysql.constants.COMMAND.COM_PING, "") 99 | self._read_ok_packet() 100 | except Exception: 101 | if reconnect: 102 | # here add action to deal the old/broken connection in pool 103 | if self._pool is not None: 104 | logger.debug('Connection had broken in pool(%s), reconnect it', self._pool.name) 105 | self._force_close() 106 | self.connect() 107 | self.ping(False) 108 | else: 109 | raise 110 | 111 | def cursor(self, cursor=None): 112 | """ 113 | Create a new cursor to execute queries with. 114 | 115 | :param cursor: The type of cursor to create. None means use Cursor. 116 | :type cursor: :py:class:`Cursor`, :py:class:`SSCursor`, :py:class:`DictCursor`, 117 | or :py:class:`SSDictCursor`. 118 | """ 119 | if cursor: 120 | if cursor.__name__ == 'DictCursor': 121 | return DictCursor(self) # custom DictCursor class in this module 122 | elif cursor.__name__ == 'Cursor': 123 | return Cursor(self) # custom Cursor class in this module 124 | else: 125 | # other type dose not has custom db_query() and db_modify() method 126 | return cursor(self) 127 | else: 128 | if self.cursorclass.__name__ == 'DictCursor': 129 | return DictCursor(self) 130 | elif self.cursorclass.__name__ == 'Cursor': 131 | return Cursor(self) 132 | else: 133 | return self.cursorclass(self) 134 | 135 | 136 | class Cursor(pymysql.cursors.Cursor): 137 | def db_query(self, query, args=()): 138 | """ 139 | A wrapped method of Cursor.fetchone() or Cursor.fetchall() when doing select query. 140 | The outer layer of return data is always list(always use cursor.fetchall()), to display data with a unified structure. 141 | """ 142 | # with self: 143 | try: 144 | # cur = self.cursor(cursorclass) if cursorclass else self.cursor() 145 | self.execute(query, args) 146 | return self.fetchall() 147 | except Exception: 148 | raise 149 | 150 | def db_modify(self, query, args=(), exec_many=False): 151 | """ 152 | A wrapped method of Cursor.execute() or Cursor.executemany() when doing modify query. 153 | return: {'rowcount': xxx, 'lastrowid': xxx} 154 | 155 | exec_many: whether use executemany() method 156 | """ 157 | # with self: 158 | try: 159 | # cur = self.cursor() 160 | if not exec_many: 161 | rt = self.execute(query, args) 162 | else: 163 | rt = self.executemany(query, args) 164 | return {'rowcount': self.rowcount, 'lastrowid': self.lastrowid} 165 | except Exception: 166 | raise 167 | 168 | 169 | class DictCursor(pymysql.cursors.DictCursorMixin, Cursor): 170 | """ 171 | A cursor which returns results as a dictionary 172 | Inheritance from the custom Cursor class 173 | """ 174 | 175 | 176 | class ConnectionPool: 177 | """ 178 | Return connection_pool object, which has method can get connection from a pool with timeout and retry feature; 179 | put a reusable connection back to the pool, etc; also we can create different instance of this class that represent 180 | different pool of different DB Server or different user 181 | """ 182 | 183 | def __init__(self, size=10, maxsize=100, name=None, pre_create_num=0, con_lifetime=3600, autocommit=True, *args, **kwargs): 184 | """ 185 | size: int 186 | normal size of the pool 187 | maxsize: int 188 | max size for scalability 189 | name: str 190 | optional pool name (str) 191 | default: host-port-user-database 192 | pre_create_num: int 193 | create specified number connections at the init phase; otherwise will create connection when really need. 194 | con_lifetime: int 195 | the max lifetime(seconds) of the connections, if it reach the specified seconds, when return to the pool: 196 | 1. if connction_number<=size, create a new connection and replace the overlifetime one in the pool; 197 | resolve the problem of mysql server side close due to 'wait_timeout' 198 | 2. If connction_number>size, close the connection and remove it from the pool. 199 | used for pool scalability. 200 | in order for the arg to work as expect: 201 | you should make sure that 'con_lifetime' is less than mysql's 'wait_timeout' variable. 202 | 0 or negative means do not consider the lifetime 203 | autocommit: bool 204 | True: the connection will be automatically committed and set the autocommit attribute of the connection object to True when returned; 205 | False: the connection will be automatically rolledback and set the autocommit attribute of the connection object to False when returned; 206 | 1.This ensures that each connection returned to the connection pool is clean and does not contain unfinished transactions. 207 | 2.Maintain a consistent autocommit setting to prevent situations where users explicitly set the autocommit attribute of the connection object. 208 | args & kwargs: 209 | same as pymysql.connections.Connection() 210 | """ 211 | self._size = size 212 | self.maxsize = maxsize 213 | self._pool = deque() 214 | self._pre_create_num = pre_create_num if pre_create_num <= maxsize else maxsize 215 | self._con_lifetime = con_lifetime 216 | self._autocommit = autocommit 217 | self._args = args 218 | self._kwargs = kwargs 219 | self.name = name if name else '-'.join( 220 | [kwargs.get('host', 'localhost'), str(kwargs.get('port', 3306)), 221 | kwargs.get('user', ''), kwargs.get('database', '')]) 222 | self._created_num = deque() # record the number of all used and available connections(use deque for thread-safe) 223 | 224 | if pre_create_num > 0: 225 | for _ in range(self._pre_create_num): 226 | conn = self._create_connection() 227 | self._pool.appendleft(conn) 228 | conn._returned = True 229 | else: 230 | self._args = args 231 | self._kwargs = kwargs 232 | 233 | def get_connection(self, retry_num=3, retry_interval=0.1, pre_ping=False): 234 | """ 235 | retry_num: int 236 | how many times will retry to get a connection 237 | retry_interval: float 238 | timeout of get a connection from pool(0 means return or raise immediately) 239 | pre_ping: bool 240 | before return a connection, send a ping command to the Mysql server, if the connection is broken, reconnect it 241 | """ 242 | if retry_num > 10: 243 | retry_num = 10 # retry_num hard limit 244 | try: 245 | conn = self._pool.pop() 246 | except IndexError: 247 | if self.total_num < self._size: 248 | return self._create_connection() 249 | if retry_num > 0: 250 | retry_num -= 1 251 | time.sleep(retry_interval) 252 | logger.debug('Retry to get connection from pool(%s)', self.name) 253 | return self.get_connection(retry_num, retry_interval, pre_ping) 254 | else: 255 | if self.total_num < self.maxsize: 256 | return self._create_connection() 257 | else: 258 | raise GetConnectionFromPoolError("can't get connection from pool({}), due to pool lack.".format(self.name)) 259 | 260 | # check con_lifetime 261 | conn._returned = False 262 | if self._con_lifetime > 0 and int(time.time()) - conn._create_ts >= self._con_lifetime: 263 | conn._pool = None 264 | try: 265 | conn.close() 266 | except: 267 | conn._force_close() 268 | self._created_num.pop() 269 | logger.debug("Close connection in pool(%s) due to lifetime reached", self.name) 270 | # loss one, create one 271 | return self._create_connection() 272 | else: 273 | if pre_ping: 274 | conn.ping(reconnect=True) 275 | 276 | logger.debug('Get connection from pool(%s)', self.name) 277 | return conn 278 | 279 | def _put_connection(self, conn): 280 | if not hasattr(conn, '_pool') or conn._pool is None: 281 | return 282 | conn.cursor().close() 283 | if not conn._returned: 284 | # consider the connection lifetime with the purpose of reduce active connections number 285 | if self._con_lifetime > 0 and int(time.time()) - conn._create_ts >= self._con_lifetime: 286 | conn._pool = None 287 | try: 288 | conn.close() 289 | except: 290 | conn._force_close() 291 | self._created_num.pop() 292 | logger.debug("Close connection in pool(%s) due to lifetime reached", self.name) 293 | if self.total_num >= self._size: 294 | conn._returned = True 295 | return 296 | conn = self._create_connection() 297 | if conn.get_autocommit(): 298 | conn.commit() 299 | else: 300 | conn.rollback() 301 | conn.autocommit(self._autocommit) 302 | conn._returned = True 303 | self._pool.appendleft(conn) 304 | logger.debug("Put connection back to pool(%s)", self.name) 305 | else: 306 | raise ReturnConnectionToPoolError("connection has already returned to the pool({})".format(self.name)) 307 | 308 | def _create_connection(self): 309 | conn = Connection(*self._args, **self._kwargs) 310 | conn._pool = self 311 | # add attr create timestamp for connection 312 | conn._create_ts = int(time.time()) 313 | # add attr indicate whether the connection has already return to pool, should not use any more 314 | conn._returned = False 315 | conn.autocommit(self._autocommit) 316 | self._created_num.append(1) 317 | logger.debug('Create new connection in pool(%s)', self.name) 318 | return conn 319 | 320 | @property 321 | def available_num(self): 322 | """available connections number for now""" 323 | return len(self._pool) 324 | 325 | @property 326 | def total_num(self): 327 | """total connections number of all used and available""" 328 | return len(self._created_num) 329 | 330 | 331 | class GetConnectionFromPoolError(Exception): 332 | """Exception related can't get connection from pool within timeout seconds.""" 333 | 334 | 335 | class ReturnConnectionToPoolError(Exception): 336 | """Exception related can't return connection to pool.""" 337 | 338 | 339 | def already_returned_conn(f): 340 | @functools.wraps(f) 341 | def wrapper(*args, **kwargs): 342 | # args[0] means self(connection object) 343 | if hasattr(args[0], '_returned') and args[0]._returned: 344 | raise ReturnConnectionToPoolError("this connection has already returned to the pool({})".format(args[0]._pool.name)) 345 | return f(*args, **kwargs) 346 | return wrapper 347 | 348 | 349 | for name, fn in inspect.getmembers(Connection, inspect.isfunction): 350 | if not name.startswith('_'): 351 | setattr(Connection, name, already_returned_conn(fn)) 352 | 353 | 354 | class ConnectionPoolSingleton(ConnectionPool): 355 | _instance = None 356 | 357 | def __new__(cls, *args, **kwargs): 358 | if cls._instance is None: 359 | cls._instance = ConnectionPool.__new__(cls) 360 | return cls._instance 361 | -------------------------------------------------------------------------------- /setup.py: -------------------------------------------------------------------------------- 1 | # -*- coding: utf-8 -*- 2 | from setuptools import setup 3 | 4 | readme = 'README.md' 5 | setup( 6 | name="pymysql-pool", 7 | version="0.4.6", 8 | url="https://github.com/jkklee/pymysql-pool", 9 | author="ljk", 10 | py_modules=['pymysqlpool'], 11 | license="GPLv3", 12 | author_email="chaoyuemyself@hotmail.com", 13 | description="MySQL connection pool based pymysql", 14 | long_description=open(readme, encoding='utf-8').read(), 15 | long_description_content_type="text/markdown", 16 | python_requires=">=3.6", 17 | install_requires=['pymysql>=0.7.10'], 18 | keywords=[ 19 | 'pymysql pool', 20 | 'mysql connection pool', 21 | 'mysql multi threads' 22 | ] 23 | ) 24 | -------------------------------------------------------------------------------- /simple-benchmark.py: -------------------------------------------------------------------------------- 1 | 2 | import pymysqlpool 3 | import pymysql 4 | import time 5 | import sys 6 | 7 | config = {'host': '192.168.1.111', 'user': 'user', 'password': 'pass', 'database': 'test'} 8 | 9 | 10 | def test_with_pymysqlpool(num): 11 | pool = pymysqlpool.ConnectionPool(size=10, maxsize=10, pre_create_num=10, name='poo', **config) 12 | t1 = time.time() 13 | for _ in range(num): 14 | con = pool.get_connection() 15 | cur = con.cursor() 16 | cur.execute('select 1+1') 17 | cur.close() 18 | con.close() 19 | t2 = time.time() 20 | print('total {} finish within {}s.\n{} queries per second, avg {} ms per query'.format(num, round(t2-t1, 3), round(num/(t2-t1), 2), round((t2-t1)*1000/num, 2))) 21 | 22 | 23 | def test_within_only_one_con(num): 24 | con = pymysql.Connection(**config) 25 | t1 = time.time() 26 | for _ in range(num): 27 | cur = con.cursor() 28 | cur.execute('select 1+1') 29 | cur.close() 30 | t2 = time.time() 31 | print('total {} finish within {}s.\n{} queries per second, avg {} ms per query'.format(num, round(t2-t1, 3), round(num/(t2-t1), 2), round((t2-t1)*1000/num, 2))) 32 | 33 | 34 | def make_conn_everytime(num): 35 | t1 = time.time() 36 | for i in range(num): 37 | con = pymysql.Connection(**config) 38 | cur = con.cursor() 39 | cur.execute('select 1+1') 40 | cur.close() 41 | con.close() 42 | t2 = time.time() 43 | print('total {} finish within {}s.\n{} queries per second, avg {} ms per query'.format(num, round(t2-t1, 3), round(num/(t2-t1), 2), round((t2-t1)*1000/num, 2))) 44 | 45 | 46 | # test use sqlalchemy 47 | # def test_sqlalchemy_connection_pool(num): 48 | # from sqlalchemy import create_engine, text 49 | # from sqlalchemy.orm import sessionmaker 50 | # db_url = 'mysql+pymysql://root:ljk.404@192.168.1.218:3306/test' 51 | # engine = create_engine(db_url, pool_size=10, max_overflow=20) 52 | # Session = sessionmaker(bind=engine) 53 | # t1 = time.time() 54 | # for _ in range(num): 55 | # with Session() as session: 56 | # result = session.execute(text('SELECT 1 + 1')) 57 | # # print(result.scalar()) 58 | # t2 = time.time() 59 | # print(t2-t1) 60 | 61 | 62 | def main(): 63 | usage = "\ 64 | Usage: {} [test_name] [test_num]\n\ 65 | test_name: [pymysql-pool | pymysql-one-conn | pymysql-new-con-everytime]\n\ 66 | test_num: a integer\ 67 | ".format(sys.argv[0]) 68 | if len(sys.argv) != 3: 69 | print(usage) 70 | else: 71 | test = sys.argv[1] 72 | num = int(sys.argv[2]) 73 | 74 | if test == 'pymysql-pool' and num: 75 | test_with_pymysqlpool(num) 76 | elif test == 'pymysql-one-conn' and num: 77 | # This is the best performing scenario, native pymysql, and all queries are done within a single connection 78 | test_within_only_one_con(num) 79 | elif test == 'pymysql-new-con-everytime' and num: 80 | # This is the worst-performing scenario, native pymysql, but a new connection is established with each query 81 | make_conn_everytime(num) 82 | else: 83 | print(usage) 84 | 85 | 86 | if __name__ == "__main__": 87 | main() 88 | --------------------------------------------------------------------------------