redis's connection pool makes me wonder

[forthcoming]

https://github.com/redis/redis-py/blob/master/redis/connection.py#L1515

def release(self, connection):
    self._checkpid()
    with self._lock:
        try:
            self._in_use_connections.remove(connection)
        except KeyError:
            pass

        if self.owns_connection(connection):
            self._available_connections.append(connection)
        else:
            # pool doesn't own this connection. do not add it back
            # to the pool and decrement the count so that another
            # connection can take its place if needed
            self._created_connections -= 1
            connection.disconnect()
            return

Since you don't own this connection, it means that the program has been fork, and _created_connections has been initialized to 0, why subtract 1 again?Can someone explain it to me?,thanks