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Don't explicitly pass a default (small) receive size, let trio choose. #185
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Thank you for the attention here. I have several concerns:
I'd be interested in trying some modest increases (2x, 4x) on our specific deployment and trying to measure the effect, but I don't have the time available right now. At best, if that looked promising, I'd consider making receive bytes able to be set in the API (including None), but still default to the current value.
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If you have a real app that is measurably benefitting from a larger buffer, that would be a useful datapoint.
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Thanks for the fast answer.
Regarding 3. and performance: I did notice this, because in a benchmark I could see my code spending a lot of time in wsproto routines that this code is calling in a loop after it receives each 4 kB of data.
So I did make it bigger, and it significantly helped with performance. I ended up doing what this PR suggests in production code, and it's faster & consuming less CPU now.
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I did make some profiling, see this repo. It's a server that repeatedly send packets.
You can run it this way:
And then you run a client:
Results before PR, for different packet size:
Results after PR, for different packet size:
So with packets of a size 1kB, it's 20% faster. Size 10 kB it's 2x faster. Size 100 kB it's 6x faster.
In terms of memory use, for this minimalistic example that loads nothing except trio+trio-websocket, the max memory consumption increase by like 0.03%, I think this is not really noticeable in the real world.
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How much less? Is your app mostly complete, or is there functionality still to add that will reduce the difference?
I don't think tiny benchmarks can guide selection of this value. And there is still the inertia of existing uses-- we can only speculate about consequences of a 16x increase.
Given the arbitrary values in both trio and trio-websocket, I'm open to plumbing through an option (but still keeping 4k as default).
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It's an application that does heavy websocket reading, and it's definitely bottlenecked by this. In my specific case it ~doubled the performance of my app.
What problems do you foresee with a 16x increase in buffer size? To be honest I don't really understand.
Anyway I sent an alternative PR for plumbing it through.