fix(das): deep-copy worker failed map in getState to avoid stats race#5057
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neyy91 wants to merge 1 commit into
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fix(das): deep-copy worker failed map in getState to avoid stats race#5057neyy91 wants to merge 1 commit into
neyy91 wants to merge 1 commit into
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getState returned workerState by value, but the embedded result's `failed` map was shared by reference with the running worker. The coordinator's unsafeStats path iterates that map (via getState) without holding the worker lock, while the worker keeps writing to it under the lock during sampling. Concurrent map iteration and map write is a fatal runtime error, so polling SamplingStats or the periodic checkpoint could crash a node that is sampling. Deep-copy the map under the lock so each snapshot is independent. Adds a regression test reproducing the concurrent read/write (fails under -race before the fix).
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Overview
worker.getState()returnedworkerStateby value, but the embeddedresult.failedmap was shared by reference with the running worker. The coordinator'sunsafeStatsiterates that map (viagetState) without holding the worker lock, while the worker keeps writing to it under the lock during sampling. Concurrent map iteration and map write is a fatal runtime error, so pollingSamplingStatsor the periodic background checkpoint could crash a sampling node.Fix: deep-copy the map under the lock so each snapshot is independent. Pausing the coordinator (the existing
stats()mechanism) does not pause workers, so the snapshot must not alias worker-owned state.Adds a regression test reproducing the concurrent read/write; it fails under
-racebefore the fix.Closes #5056