Tune the locking in ConnectionPool.get_connection

The lock does not need to be held while waiting for the socket to establish and validate the TCP connection.

Author: andymccurdy

CHANGES

@@ -1,3 +1,7 @@
+* 3.5.2 (May 14, 2020)
+ * Tune the locking in ConnectionPool.get_connection so that the lock is
+ not held while waiting for the socket to establish and validate the
+ TCP connection.
 * 3.5.1 (May 9, 2020)
  * Fix for HSET argument validation to allow any non-None key. Thanks
  @AleksMat, #1337, #1341

redis/connection.py

@@ -1098,7 +1098,7 @@ def __repr__(self):
  )
 
  def reset(self):
- self._lock = threading.RLock()
+ self._lock = threading.Lock()
  self._created_connections = 0
  self._available_connections = []
  self._in_use_connections = set()
@@ -1177,28 +1177,29 @@ def get_connection(self, command_name, *keys, **options):
  except IndexError:
  connection = self.make_connection()
  self._in_use_connections.add(connection)
+
+ try:
+ # ensure this connection is connected to Redis
+ connection.connect()
+ # connections that the pool provides should be ready to send
+ # a command. if not, the connection was either returned to the
+ # pool before all data has been read or the socket has been
+ # closed. either way, reconnect and verify everything is good.
  try:
- # ensure this connection is connected to Redis
+ if connection.can_read():
+ raise ConnectionError('Connection has data')
+ except ConnectionError:
+ connection.disconnect()
  connection.connect()
- # connections that the pool provides should be ready to send
- # a command. if not, the connection was either returned to the
- # pool before all data has been read or the socket has been
- # closed. either way, reconnect and verify everything is good.
- try:
- if connection.can_read():
- raise ConnectionError('Connection has data')
- except ConnectionError:
- connection.disconnect()
- connection.connect()
- if connection.can_read():
- raise ConnectionError('Connection not ready')
- except BaseException:
- # release the connection back to the pool so that we don't
- # leak it
- self.release(connection)
- raise
-
- return connection
+ if connection.can_read():
+ raise ConnectionError('Connection not ready')
+ except BaseException:
+ # release the connection back to the pool so that we don't
+ # leak it
+ self.release(connection)
+ raise
+
+ return connection
 
  def get_encoder(self):
  "Return an encoder based on encoding settings"