How can I reduce memory usage of a Twisted server?

Question

I wrote an audio broadcasting server with Python/Twisted. It works fine, but the usage of memory grows too fast! I think that's because some user's network might not be good enough to download the audio in time.

My audio server broadcast audio data to different listener's client, if some of them can't download the audio in time, that means, my server keep the audio data until listeners received. And what's more, my audio server is a broadcasting server, it receive audio data, and send them to different clients, I though Twisted copy those data in different buffer, even they are same audio piece.

I want to reduce the usage of memory usage, so I need to know when is the audio received by the client, so that I can decide when to discard some slow clients. But I have no idea how to achieve that with Twisted. Do anyone have idea?

And what else can I do to reduce usage of memory usage?

Thanks. Victor Lin.

Answer 1

Make sure you're using Python's garbage collector and then go through and delete variables you aren't using.

Answer 2

You didn't say, but I'm going to assume that you're using TCP. It would be hard to write a UDP-based system which had ever increasing memory because of clients who can't receive data as fast as you're trying to send it.

TCP has built-in flow control capabilities. If a receiver cannot read data as fast as you'd like to send it, this information will be made available to you and you can send more slowly. The way this works with the BSD socket API is that a send(2) call will block or will return 0 to indicate it cannot add any bytes to the send buffer. The way it works in Twisted is by a system called "producers and consumers". The gist of this system is that you register a producer with a consumer. The producer calls write on the consumer repeatedly. When the consumer cannot keep up, it calls pauseProducing on the producer. When the consumer is again ready for more data, it calls resumeProducing on the producer.

You can read about this system in more detail in the producer/consumer howto, part of Twisted's documentation.