opt(s2n-quic-dc): clamp TCP server concurrency #2827
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The lock contention referenced in the comment is a significant problem as the number of cores increases. In the future we can consider other mitigations for it (e.g., io_uring's fixed fd pool), but that's not possible until we can raise our minimal kernel baseline and is a much larger effort.
Mark-Simulacrum
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boquan-fang
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Sep 24, 2025
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Release Summary:
Resolved issues:
n/a
Description of changes:
The lock contention referenced in the comment is a significant problem as the number of cores increases. In the future we can consider other mitigations for it (e.g., io_uring's fixed fd pool), but that's not possible until we can raise our minimal kernel baseline and is a much larger effort.
Call-outs:
n/a
Testing:
Testing the # of spawns is pretty annoying. I don't think I have any off-by-one logic here but in the worst case 4 becomes 5 or 3, and either is fine too; 4 is not some specially chosen magic number, just "not too high".
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.