今天在寫zabbix storm job監控腳本的時候用到了python的redis模塊，之前也有用過，但是沒有過多的了解，今天看了下相關的api和源碼,看到有ConnectionPool的實現，這里簡單說下。
在ConnectionPool之前，如果需要連接redis，我都是用StrictRedis這個類，在源碼中可以看到這個類的具體解釋：
 
redis.StrictRedis Implementation of the Redis protocol.This abstract class provides a Python interface to all Redis commands and an
implementation of the Redis protocol.Connection and Pipeline derive from this, implementing how the commands are sent and received to the Redis server

使用的方法：
 

 r=redis.StrictRedis(host=xxxx, port=xxxx, db=xxxx) r.xxxx()

有了ConnectionPool這個類之后，可以使用如下方法
 

pool = redis.ConnectionPool(host=xxx, port=xxx, db=xxxx)r = redis.Redis(connection_pool=pool)

這里Redis是StrictRedis的子類
簡單分析如下：
在StrictRedis類的__init__方法中，可以初始化connection_pool這個參數，其對應的是一個ConnectionPool的對象：
 

class StrictRedis(object):........  def __init__(self, host='localhost', port=6379,         db=0, password=None, socket_timeout=None,         socket_connect_timeout=None,         socket_keepalive=None, socket_keepalive_options=None,         connection_pool=None, unix_socket_path=None,         encoding='utf-8', encoding_errors='strict',         charset=None, errors=None,         decode_responses=False, retry_on_timeout=False,         ssl=False, ssl_keyfile=None, ssl_certfile=None,         ssl_cert_reqs=None, ssl_ca_certs=None):     if not connection_pool:       ..........       connection_pool = ConnectionPool(**kwargs)     self.connection_pool = connection_pool

在StrictRedis的實例執行具體的命令時會調用execute_command方法，這里可以看到具體實現是從連接池中獲取一個具體的連接，然后執行命令，完成后釋放連接：

  # COMMAND EXECUTION AND PROTOCOL PARSING  def execute_command(self, *args, **options):    "Execute a command and return a parsed response"    pool = self.connection_pool    command_name = args[0]    connection = pool.get_connection(command_name, **options) #調用ConnectionPool.get_connection方法獲取一個連接    try:      connection.send_command(*args) #命令執行，這里為Connection.send_command      return self.parse_response(connection, command_name, **options)    except (ConnectionError, TimeoutError) as e:      connection.disconnect()      if not connection.retry_on_timeout and isinstance(e, TimeoutError):        raise      connection.send_command(*args)       return self.parse_response(connection, command_name, **options)    finally:      pool.release(connection) #調用ConnectionPool.release釋放連接