Fix deadlock in cmdio tea program queueing#5505
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acquireTeaProgram blocked on teaDone while holding teaMu, but releaseTeaProgram needs teaMu to close that channel, so queueing a second tea.Program behind an active one deadlocked both goroutines. Wait with the lock released and re-check in a loop before registering. Co-authored-by: Isaac
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Commit: 4d5c4c4
22 interesting tests: 15 SKIP, 7 KNOWN
Top 29 slowest tests (at least 2 minutes):
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Co-authored-by: Isaac
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pietern
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Jun 10, 2026
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I want to get rid of this when we can and allocate a single tea.Program for the lifetime of the command instead of swapping in and out. Needs a close look.
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Why
Found during a full-repo review of the CLI.
acquireTeaPrograminlibs/cmdiois documented to queue a newtea.Programbehind an active one, but it waits on theteaDonechannel while holdingteaMu.releaseTeaProgramneeds that same mutex to close the channel, so the moment two programs overlap, both goroutines deadlock and the CLI hangs. It is latent today because callers happen to serialize, but any future concurrent spinner or prompt would trip it.Changes
Before, starting a second
tea.Programwhile one was active deadlocked; now the second one waits for the active program to finish and then runs.acquireTeaProgramcopiesteaDoneunder the lock, releases the lock while waiting on the channel, and re-checks in a loop before registering, since another acquirer may take the slot first.releaseTeaProgramandWaitare unchanged.Test plan
TestAcquireTeaProgramWaitsForReleaseinlibs/cmdio/io_test.go: starts a second acquire while a program is active, asserts it queues, then asserts it completes after release, with a timeout guarding against deadlockgo test -race ./libs/cmdio/...passes./task fmt-q,./task lint-q, and./task checkspassThis pull request and its description were written by Isaac.