> the size of the _putters list is constrained by per-process open file limits
there is no mechanism to restrict this inherent in the Queue class, it would be up to the caller to use the class with that restriction > every _putter represents a socket no, their design for the Queue is for it to be used by async callers (coroutines) so there would never be more than 1 entry in the getters and/or putters. In the specific use case modified by this patch, the WebSocketClientConnection class is updated to use the Queue class and, from its on_message method, return the future object representing the item put into the Queue. If the Queue has room for the object, its future object is the 'gen._null_future' object which is always completed (and whose result it None, but that doesn't matter). If the Queue doesn't have room, it returns a real future object that won't be completed until something calls the Queue's get() to take it off the putters deque. The caller of WebSocketClientConnection.on_message() is thus responsible for performing the queue throttling by using the returned future object. In this case, that caller is WebSocketProtocol13._handle_message(), which returns the future provided by the call to on_message. The caller of _handle_message() is WebSocketProtocol13._on_frame_data(), that sets its local var handled_future to the future returned from the Queue. It then adds a callback to be called when the future is done, to call self._receive_frame(); in previous behavior, there was no future object returned from on_message (and thus _handle_message also returned None) so _on_frame_data() immediately called self._receive_frame(), which is what could lead to unthrottled filling of the queue. Now that _on_frame_data() does get a future object and defers self._receive_frame() to execution only after the current message waiting in the Queue._putters deque has been removed, the Queue should never have more than a single message waiting in its putters. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1903733 Title: Out of memory issue for websocket client To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/python-tornado/+bug/1903733/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
