Two telemetry events, one mangled line
O_APPEND only guarantees non-interleaved writes below PIPE_BUF, which is 4096 bytes on Linux. A fat JSONL event above that splices two lines.
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4 pages
Concurrency
Process isolation won't save you from the filesystem
A flaky self-update test: separate processes still shared a computed cache path and raced on disk. Process isolation is not filesystem isolation.
A mutex on a flag nobody writes twice
Why a write-once boolean still needs a mutex: the Go memory model needs a happens-before edge before another goroutine is guaranteed to see it.
The test-mocking pattern that races
Reassigning a package-level function variable in tests is a latent data race that t.Parallel exposes. The fix is structural, not another lock.
