test(lint-shellcheck): deterministic barrier for worker-cap concurrency proof - #542
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…a file barrier test_default_worker_cap used sleep 0.1 inside the ShellCheck stub to widen a race window for observing two-way concurrency, which QA rules forbid and which host load can silently weaken (max_active could observe 1 even when the real cap is 2, since the old assertion only required >= 1). Workers now register at a flock-serialized counter and all release together once exactly two are concurrently registered, making the max_active == 2 assertion a deterministic property of the protocol. A bounded 5s deadline fails the stub with a clear message instead of hanging if the cap ever degrades to 1. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0177ds9nxEMtsh3bwpBxNHYx
qa-tester's gate review correctly flagged that the bounded busy-wait (sleep-in-a-loop) still counted as forbidden sleep-based synchronization. Switch to a blocking read on a bidirectionally-opened FIFO (open O_RDWR never blocks, sidestepping the open()-hangs-forever failure mode a prior ticket hit with a read-only/write-only FIFO) with a bounded -t timeout as the only failure path, and reuse the repo's existing serialize_with_lock helper for the counter mutex instead of a bespoke flock call (critic's portability finding). Also fixed the fixture's total shell-file count, which was odd and left the last worker of the sliding window unpaired. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0177ds9nxEMtsh3bwpBxNHYx
…ner wakes qa-tester's second gate round found that the releasing worker wrote its release signal and immediately proceeded toward deregistration without confirming the released worker actually woke up -- under a hypothetical cap-3 regression, both original workers could deregister before a concurrently-forked third worker reached the counter lock, letting the observed max_active read 2 even though 3 were briefly resident. Add a second FIFO for a blocking ack: the releaser now waits for the released worker's ack before either side deregisters, closing that asymmetric fast-exit window. Verified with a jobs=3 mutation of the fixture's copy of lint-shellcheck.sh -- the test now observes max_active=6 and fails, where it previously would have reported 2 and passed. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0177ds9nxEMtsh3bwpBxNHYx
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Summary
test_default_worker_capusedsleep 0.1inside the ShellCheck stub to widen a race window for observing two-way concurrency, which QA rules forbid and which host scheduling could silently weaken (the old assertion only requiredmax_active >= 1, so it would pass even without genuine overlap).serialize_with_lockand block on a blocking FIFO read (bounded 5s timeout, never a polling sleep) until a second worker signals release; a second FIFO carries an ack so the releasing worker doesn't exit before the released worker actually wakes, closing an asymmetric fast-exit window a gate reviewer found.max_active == 2(a real, deterministic proof of overlap) instead of>= 1. If the real cap ever collapses to 1, the lone worker's bounded FIFO read times out and fails with a clear message instead of hanging (avoiding the FIFO-open hang shape from CC-543).Test plan
bash tests/shell/test-lint-shellcheck.sh(17/17, including the changed case, run 5x for stability)tools/lint/lint-shellcheck.shclean on the whole repolint-shellcheck.sh: confirmed the barrier now observesmax_active=6and fails, where it previously would have silently reported 2 and passedpmctl gate run --executor codex --policy generic→ GO (after 2 remediation rounds: portable-lock reuse + sleep-free blocking wait, then the ack-handshake fix)tests/bin/run-all-tests.sh→ 104 passed, 0 failed, 0 skipped🤖 Generated with Claude Code
https://claude.ai/code/session_0177ds9nxEMtsh3bwpBxNHYx