Reduce server load from the WebSocket server #566
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Previously, the server was encoding and compressing each message for every client. This resulted in high server load, to the point that the WebSocket server couldn't keep up and dropped messages. Unfortunately, the websockets package doesn't officially expose its innards. Therefore, this is a disgusting hack that inspects the enabled extensions, prepares the data, and then sends that directly, all using internal APIs of websockets version 7.0. Compression (cf. RFC 7692) introduces a further complexity: context takeover. Normally, the compression context is reused across messages, but because clients connect at different times and might not be receiving all messages, the same compressor cannot be used across connections. Therefore, context takeover is disabled here. This also adds some stats about the throughput.
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Already running in prod anyway, so merging. |
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Previously, the server was encoding and compressing each message for every client. This resulted in high server load, to the point that the WebSocket server couldn't keep up and dropped messages.
Unfortunately, the websockets package doesn't officially expose its innards. Therefore, this is a disgusting hack that inspects the enabled extensions, prepares the data, and then sends that directly, all using internal APIs of websockets version 7.0.
Compression (cf. RFC 7692) introduces a further complexity: context takeover. Normally, the compression context is reused across messages, but because clients connect at different times and might not be receiving all messages, the same compressor cannot be used across connections. Therefore, context takeover is disabled here.
This also adds some stats about the throughput.