fix: adaptive engine crash + erratic H1 performance#43
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FumingPower3925 merged 4 commits intomainfrom Mar 9, 2026
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- Replace MSG_PEEK-based protocol detection with inline detection in handleRecv, fixing 20x slowdown on arm64 where MSG_PEEK behaves differently. Detection now happens on first received data, matching epoll's approach. - Remove dead code: prepRecvPeek, udPeek, msgPeek, handlePeek. - Eliminate per-DATA-frame map allocation in FlushWindowUpdates by writing WINDOW_UPDATE frames directly while iterating pending updates. - Lower windowUpdateThreshold from 16384 to 1024 so small bodies (4KB) get timely flow control credits on multiplexed connections. - Clean up pendingStreamUpdates in DeleteStream to prevent unbounded map growth over long-lived connections.
Three root causes addressed: 1. Crash on hybrid (Auto) mode: both sub-engines created NumCPU workers each, exhausting io_uring ring resources on low-CPU machines. Added splitResources() to halve shared resources per sub-engine while keeping per-connection settings unchanged. Lowered MinWorkers to 1. 2. Dead telemetry: standby engine always scored 0 (PauseAccept → zero traffic → zero RPS), making the controller a permanent no-op. Replaced live standby sampling with historical scoring — stores last active score per engine type with 1%/sec decay. Standby seeded at 80% of active when no history exists. 3. CPU contention: standby workers busy-polled even when idle, wasting ~50% CPU. Added timeout backoff for idle standby workers (1s for io_uring, 500ms for epoll) when accept is paused and no connections are draining. Closes #42
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Summary
Fixes three root causes behind Issue #42 (adaptive engine crash + erratic H1 benchmark performance):
NumCPUworkers each, exhausting io_uring ring resources on 2-vCPU CI machines. AddedsplitResources()to halve shared resources (workers, ring size, buffer pool, max events, max conns) per sub-engine. LoweredMinWorkersfrom 2 to 1.PauseAccept→ zero traffic → zero RPS, so the switch condition0 > activeScore * 1.15was always false. Replaced live standby sampling with historical scoring — stores the last active score per engine type with 1%/sec decay. New standby engines are seeded at 80% of active's score.Files changed
adaptive/engine.gosplitResources()+New()uses halved configsadaptive/controller.goevaluate()rewrite,historicalScore()adaptive/engine_test.goengine/iouring/worker.goengine/epoll/loop.goresource/preset.goMinWorkers2→1resource/preset_test.goresource/config_test.goTest plan
go build ./...(macOS, linux/amd64, linux/arm64)go test -race -count=1 ./resource/...— passgo test -race -count=1 ./overload/...— pass (no regressions)go test -race -count=1 ./...— all pass (4 pre-existing h2spec failures unrelated)golangci-lint run ./...— 0 issues (macOS + linux/amd64)go test -v -race ./adaptive/...(linux only)go test -v -race ./test/integration/...(linux only)Closes #42