Memory leaks due connections left open?

[Petr Lefner]

Using swiftclient.service.SwiftService context manager object, I am observing consistently increasing memory consumption along invokes of stat() or download() methods:

while True:
    with SwiftService(...) as swift:
        for stat_futures in swift.stat(container, objects=[...]):
            ...

    sleep(1)

Note the memory impact does not change even upon moving the object outside while loop. Running a docker container executing this code, docker stats command reports consistently increasing memory usage, until process has been killed at the moment reaching container memory limit.

I have localized the cause and possible issue within swiftclient.multithreading.ConnectionThreadPoolExecutor class. Apparently, the MultiThreadingManager object, which maintains a series of thread pool executors, desires to act iself as context manager. While it invokes __exit__ on all of its executors, none of these executors empties its "connection pool" (hold by means of queue.PriorityQueue) closing stored connections first.

Indeed, upon I added following method to body of ConnectionThreadPoolExecutor, consumed memory stabilized at nearly consistent level:

    def __exit__(self, exc_type, exc_value, traceback):
        # Close all HTTP connections when the object is exited
        while not self._connections.empty():
            _, conn = self._connections.get()
            if conn is not None:
                conn.close()
        super().__exit__(exc_type, exc_value, traceback)

Maybe I am missing somtehing, as I've found no reference about how should client code be aware of pooled connections?