Connection is not thread-safe

[gloryfromca]

Version: redis==2.10.6

Platform: Python 3.7 on Ubuntu 18.04

Description:
I encountered the same question with the link: celery/celery#4363

I reproduce the error by inserting time.sleep() in Connection.connect which is trying to initialize self._sock, then start two thread, make both pass self._sock existence check and run into Connection._on_connect (apprently Connection.connnect without any thread-lock).

So when one thread in on_connect() call read_response, it maybe get another thread's response, then raise the error.

def on_connect(self):
    "Initialize the connection, authenticate and select a database"
    self._parser.on_connect(self)

    # if a password is specified, authenticate
    if self.password:
        self.send_command('AUTH', self.password)
        if nativestr(self.read_response()) != 'OK':
            raise AuthenticationError('Invalid Password')

    # if a database is specified, switch to it
    if self.db:
        self.send_command('SELECT', self.db)
        res = self.read_response()
        if nativestr(res) != 'OK':
            raise ConnectionError('Invalid Database')

Is this a bug or something I don't get?

[andymccurdy]

Connections are not meant to be threadsafe. ConnectionPools are threadsafe.

[wynemo]

@andymccurdy #906 it seems the default connectionpool is not threading safe.