Fix Windows zombie process on shutdown - #2248
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When Stop() is called, it now waits for reloadLoop to finish via a done channel with a 15-second timeout. If goroutines are stuck in blocking syscalls (e.g., PdhCollectQueryData on Windows when PDH is broken), Go cannot interrupt them. Previously, Stop() returned immediately, telling Windows SCM the service was stopped while the process remained alive as an unkillable zombie. This fix ensures: - Normal shutdown: Stop() waits for done channel, returns cleanly - Stuck shutdown: After 15s timeout, os.Exit(1) forces process exit The 15s timeout is under Windows default WaitToKillServiceTimeout (20s). Fixes: V2288965817 (ES2 escalation - DB Systel GmbH)
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Binary Size Reportlinux/amd64
linux/arm64
windows/amd64
Investigating size changesUse go-size-analyzer to compare binaries: GOEXPERIMENT=jsonv2 go install github.com/Zxilly/go-size-analyzer/cmd/gsa@latest
gsa diff --old <baseline-binary> --new <new-binary> |
os.Exit() tries to clean up Go runtime (run finalizers, stop goroutines) which blocks when threads are suspended. syscall.Exit() calls ExitProcess directly without cleanup, ensuring the process actually terminates. Discovered during manual repro testing on Windows Server 2022.
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Problem
When Stop() is called on Windows, it returns immediately without waiting for goroutines. If a goroutine is blocked in a syscall (e.g., PdhCollectQueryData when PDH is broken), the process remains alive as an unkillable zombie.
Customer impact: Cannot restart agent, cannot kill process, only reboot recovers.
Solution
Add a done channel that reloadLoop closes on exit. Stop() waits for it with 15s timeout, then os.Exit(1) if stuck.
Testing