Fix data race on error recording in ErrSizedGroup - #14
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Previously, a worker stored the result of g.err.append(err) back into g.err while a canceled Go call read the same field outside the lock, which the race detector flags. MultiError.append mutates and returns its own receiver, so the assignment was redundant; dropping it makes the field write-once and removes the need for errLock, as MultiError is already thread safe on its own.
The cancel tests allowed 110 started goroutines, but 111 is reachable: 100 submitted before the cancellation, up to 10 running and one more waiting for the semaphore.
Coverage Report for CI Build 32187480544Coverage decreased (-0.03%) to 98.837%Details
Uncovered ChangesNo uncovered changes found. Coverage RegressionsNo coverage regressions found. Coverage Stats
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umputun
approved these changes
Aug 18, 2026
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Previously, a worker stored the result of
g.err.append(err)back intog.errwhile aGocall which observed a canceled context read the same field outside the lock, and the race detector reports it as a data race.MultiError.appendmutates and returns its own receiver, so the assignment was redundant. After this change the field is only set in the constructor, which also makeserrLockunnecessary, asMultiErroris thread safe on its own.TestErrorSizedGroup_CancelWithActiveErrorscovers the case and fails undergo test -racewithout the fix.The two cancel tests allowed 110 started goroutines, but 111 is reachable: 100 submitted before the cancellation, up to 10 running and one more waiting for the semaphore. The bound is 120 now.