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Cap UDP stress orchestrator bursts to fit OS receive buffers - #392
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The echo-verification oracle assumes zero datagram loss, so any kernel drop hangs the test. Three burst dimensions can overflow the server's UDP receive buffer on localhost: - Byte volume: the old 2 MB cap exceeded every platform's default receive buffer (Linux ~212 KB, Windows ~64 KB). Lower to 64 KB. - Datagram count: each datagram costs ~700 bytes of kernel SKB overhead regardless of payload size, so a burst of 2400 one-byte datagrams consumed ~1.8 MB of buffer. Cap at 200 datagrams. - Scheduling contention: too few scheduler threads relative to clients delays socket reads long enough for the kernel to drop. Floor ponymaxthreads at roughly 2/3 the client count, and cap clients at 1.5× the available threads.
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The echo-verification oracle assumes zero datagram loss, so any kernel drop hangs the test. Three burst dimensions can overflow the server's UDP receive buffer on localhost:
Byte volume — the old 2 MB cap exceeded every platform's default receive buffer (Linux ~212 KB, Windows ~64 KB). Lowered to 64 KB.
Datagram count — each datagram costs ~700 bytes of kernel SKB overhead regardless of payload size, so a burst of 2400 one-byte datagrams consumed ~1.8 MB of buffer. Capped at 200 datagrams.
Scheduling contention — too few scheduler threads relative to clients delays socket reads long enough for the kernel to drop. Floored
ponymaxthreadsat roughly 2/3 the client count, and capped clients at 1.5× the available threads.50 seeds pass locally on a 16-core Linux machine. CI runners (Linux/Windows) have
max_threads=2, which clamps clients to 3 — all 10 CI seeds produce bursts well within buffer limits.