🚨 test: Fix race condition in TestTimeout_ContextPropagation#4119
🚨 test: Fix race condition in TestTimeout_ContextPropagation#4119adrian-lin-1-0-0 wants to merge 3 commits intogofiber:mainfrom
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Summary of ChangesHello, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request focuses on improving the stability and accuracy of a critical test case for the timeout middleware. It resolves a race condition that could lead to flaky test results and enhances the test's ability to verify correct context propagation under timeout conditions, ensuring the middleware behaves as expected. Highlights
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🚧 Files skipped from review as they are similar to previous changes (1)
WalkthroughUpdates TestTimeout_ContextPropagation to observe handler completion via a buffered error channel ( Changes
Estimated code review effort🎯 2 (Simple) | ⏱️ ~10 minutes Possibly related PRs
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Code Review
This pull request addresses a race condition in the TestTimeout_ContextPropagation test by replacing an atomic.Bool with a buffered channel for proper synchronization between the test goroutine and the handler goroutine. The changes also improve the test by using time.NewTimer to prevent resource leaks and by strengthening the assertions to check for the specific context.DeadlineExceeded error. The fix is well-implemented and effectively resolves the race condition, making the test more robust and reliable. I have reviewed the changes and found no issues.
adrian-lin-1-0-0
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Pull request overview
Improves reliability of the timeout middleware test suite by removing a race in TestTimeout_ContextPropagation and making the assertion depend on synchronized handler observation of context cancellation (relates to #3671).
Changes:
- Replace
atomic.Boolwith a bufferederrChto synchronize between the abandoned handler goroutine and the test. - Strengthen the test to assert the handler reports
context.DeadlineExceededand to fail fast if the handler never reports.
| timer := time.NewTimer(500 * time.Millisecond) | ||
| defer timer.Stop() | ||
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| select { | ||
| case <-timer.C: | ||
| errCh <- nil | ||
| return c.SendString("completed") | ||
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| case <-c.Context().Done(): | ||
| contextCanceled.Store(true) | ||
| errCh <- c.Context().Err() | ||
| return c.Context().Err() | ||
| case <-time.After(500 * time.Millisecond): | ||
| return c.SendString("completed") | ||
| } |
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The handler’s select can become nondeterministic if it isn’t scheduled until after both the 500ms timer has fired and c.Context().Done() is already closed; in that case Go may choose the timer branch and send nil, making this test flaky even though the context was canceled. To make the assertion deterministic, prefer a pattern that prioritizes the canceled context (e.g., check c.Context().Err()/Done() first in a non-blocking way before waiting on the timer), or make the timer duration so large that it can’t realistically become ready before the handler observes cancellation.
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The timer is 500ms while the timeout is 50ms — a 10x gap. For both cases to be ready simultaneously, the goroutine would need to go unscheduled for 500ms, which is not realistic in practice.
This is also the same select pattern used in other tests in this file (e.g. TestTimeout_PanicAfterTimeout, TestTimeout_ContextCleanup) and in the existing sleepWithContext helper. Changing only this test to a different pattern would be inconsistent.
Dismissing this as not actionable.
middleware/timeout/timeout_test.go
Outdated
| select { | ||
| case handlerErr := <-errCh: | ||
| require.ErrorIs(t, handlerErr, context.DeadlineExceeded, "handler should report DeadlineExceeded") | ||
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| case <-time.After(1 * time.Second): |
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The select timeout uses time.After(1s). In repeated runs (e.g., -count=500) this leaves many pending timers until they fire, which can add avoidable allocations and noise. Prefer a time.NewTimer with defer Stop() (using timer.C in the select) so the timer can be stopped/drained when the handlerErr case wins.
| select { | |
| case handlerErr := <-errCh: | |
| require.ErrorIs(t, handlerErr, context.DeadlineExceeded, "handler should report DeadlineExceeded") | |
| case <-time.After(1 * time.Second): | |
| timer := time.NewTimer(1 * time.Second) | |
| defer func() { | |
| if !timer.Stop() { | |
| <-timer.C | |
| } | |
| }() | |
| select { | |
| case handlerErr := <-errCh: | |
| require.ErrorIs(t, handlerErr, context.DeadlineExceeded, "handler should report DeadlineExceeded") | |
| case <-timer.C: |
adrian-lin-1-0-0
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Description
Fix a potential race condition in
TestTimeout_ContextPropagationand strengthen its assertions. The original test usedatomic.Boolwhich could be read before the handler goroutine had written to it, since the timeout middleware returns immediately via the Abandon mechanism. This change replaces it with a buffered channel for proper synchronization.Relates to #3671
How to reproduce the race (before this fix)
go test -run TestTimeout_ContextPropagation -count=500 ./middleware/timeout/output
Changes introduced
List the new features or adjustments introduced in this pull request. Provide details on benchmarks, documentation updates, changelog entries, and if applicable, the migration guide.
Type of change
Checklist
/docs/directory for Fiber's documentation.Commit formatting
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