issue : pool reallocates non-free connection whenever use multi method

asyncio_redis.pool.py

def _get_free_connection(self):
        """
        Return the next protocol instance that's not in use.
        (A protocol in pubsub mode or doing a blocking request is considered busy,
        and can't be used for anything else.)
        """
        self._shuffle_connections()

        for c in self._connections:
            if c.protocol.is_connected and not c.protocol.in_use:
                return c
                

asyncio_redis.protocol.py

asyncio_redis.protocol.py


    @asyncio.coroutine
    def multi(self, watch:(ListOf(NativeType),NoneType)=None) -> 'Transaction':
        if (self._in_transaction):
            raise Error('Multi calls can not be nested.')

        # Call watch
        if watch is not None:
            for k in watch:
                result = yield from self._query(b'watch', self.encode_from_native(k))
                assert result == b'OK'

        # Call multi
        result = yield from self._query(b'multi')
        assert result == b'OK'

        self._in_transaction = True
        self._transaction_response_queue = deque()

        # Create transaction object.
        t = Transaction(self)
        self._transaction = t
        return t
        
    @property
    def in_use(self):
        """ True when this protocol is in use. """
        return self.in_blocking_call or self.in_pubsub or self.in_transaction

1. One task calls "pool.multi" method
2. "pool.multi" method uses "_get_free_connection()"
3. "_get_free_connection" method reads "self.in_transaction" in protocol's "in_use" property.
4. Because "self.in_transaction" is False, return connection and call "multi" method in "protocol.py"
5. When execute line number 16 in above "asyncio_redis.protocol.py", issue context switching.
6. Another task calls "pool.multi" method
7. "pool.multi" method uses "_get_free_connection"
8. "_get_free_connection" method reads "self.in_transaction" in protocol's "in_use" property.
9. Because "self.in_transaction" is still False, return same connection and call "multi" method in "protocol.py"
10. Redis server issues error "MULTI calls cannot be nested". It is not executing line number 7 of above "asyncio_redis.protocol.py" but replying server error.