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https://issues.apache.org/jira/browse/YUNIKORN-3387?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated YUNIKORN-3387:
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Labels: pull-request-available (was: )
> Deterministic synctest reproduction pilot
> -----------------------------------------
>
> Key: YUNIKORN-3387
> URL: https://issues.apache.org/jira/browse/YUNIKORN-3387
> Project: Apache YuniKorn
> Issue Type: Test
> Components: core - scheduler, shim - kubernetes
> Reporter: Dale Richardson
> Assignee: Dale Richardson
> Priority: Minor
> Labels: pull-request-available
>
> A pilot using Go's testing/synctest to turn a probabilistic data-race soak
> into a
> deterministic millisecond test, and to document the pattern for future
> FSM/lock
> interleaving tests.
> h3. Design
> Reproduce the YUNIKORN-3376 Task.pod race (SetTaskPod vs
> checkPodMetadataBeforeScheduling) deterministically: run the two conflicting
> operations as goroutines inside a synctest bubble, ordered by the bubble's
> fake
> clock, joined on a bubble-local WaitGroup; the race detector is the oracle.
> The
> file header documents the reusable recipe and two non-obvious traps (ordering
> must
> come from the fake clock, not from sequencing through the root goroutine via
> synctest.Wait; the root must durably block).
> h3. Results
> On the fixed tree (#1070 merged) it passes. With the fix reverted it fires
> the race
> detector deterministically 5/5 runs, all three orderings -- versus the old
> ~60s
> probabilistic soak.
> h3. Constraint found (documented)
> synctest is viable here only with go-deadlock detection off: go-deadlock arms
> a
> pooled time.AfterFunc per lock acquisition, and resetting a bubble-allocated
> timer
> outside the bubble is a fatal error that kills the whole test binary. The test
> therefore skips itself when deadlock tracking is enabled (guarded on the core
> locking flag, which the shim's locking delegates to). Consequence to weigh:
> because
> make test / CI run with detection enabled, this test is skipped in CI as
> configured
> -- it guards `go test -race` runs without detection. Scope for future use:
> looplab/fsm starts no goroutines, so object-level FSM interleavings are in
> reach;
> anything routed through the dispatcher stays with the chaos harness.
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