feat: add stderr heartbeat with deadlock diagnosis and prevention#953

Draft

devin-ai-integration[bot] wants to merge 14 commits intomainfrom

devin/1773412868-nonblocking-stdout

Commits on Mar 13, 2026

feat: non-blocking stdout writes to prevent deadlock on pipe backpressure
devin-ai-integration[bot]
committed
fix: handle UnsupportedOperation from fileno() in test environments and log restore failures
devin-ai-integration[bot]
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fix: use sys.__stdout__ to get real fd when PRINT_BUFFER replaces sys.stdout
devin-ai-integration[bot]
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fix: fall back to print() when sys.stdout is replaced (capsys/PRINT_BUFFER)
devin-ai-integration[bot]
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fix: detect capsys/redirected stdout via fileno comparison, remove PRINT_BUFFER wrapper
devin-ai-integration[bot]
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fix: use dedicated writer thread instead of non-blocking fd to avoid global BlockingIOError
devin-ai-integration[bot]
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fix: catch Exception instead of BaseException in writer thread, re-raise KeyboardInterrupt/SystemExit
devin-ai-integration[bot]
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feat: add diagnostic logging to stdout writer thread to track pipe write timing
devin-ai-integration[bot]
committed

Commits on Mar 31, 2026

feat: add thread dumps and queue stats to heartbeat for deadlock diagnosis

devin-ai-integration[bot]
and
Anatolii Yatsuk (tolik0)
committed

Commits on Apr 1, 2026

fix: prevent deadlock when main thread puts on full queue

devin-ai-integration[bot]
and
Anatolii Yatsuk (tolik0)
committed