Add detailed logging on AsyncProcess to help diagnose hangs #9275
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See swiftlang#9274 for context. The existing logging is insufficient to diagnose hangs in AsyncProcess, so adding more detailed logging around process start, output, and termination should help identify where things are going wrong. - Added `SWIFTPM_DEBUG_PROCESS_IO` environment variable to enable low-level I/O thread debugging without interfering with normal observability output - Added `processTrackingID` (8-character UUID prefix) to uniquely identify each process instance in logs for correlation across multiple concurrent processes - Added `logProcessIODebug()` helper that writes directly to stderr when debug mode is enabled, bypassing all handlers to capture issues even when the observability system has problems - Instrumented all critical synchronization points in the I/O thread lifecycle After this change, AsyncProcess will log detailed information about process lifecycle events, including when processes are started, when output is received, and when processes terminate. This should provide better visibility into where hangs may be occurring during dependency resolution. Users experiencing hangs can now run: ``` SWIFTPM_DEBUG_PROCESS_IO=1 swift package resolve 2>&1 | tee debug.log ```
bc-lee requested review from bkhouri, bripeticca, cmcgee1024, daveyc123, dschaefer2, jakepetroules, owenv, plemarquand, rconnell9 and shawnhyam as code owners Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
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Motivation:
See #9274 for context.
The existing logging is insufficient to diagnose hangs in AsyncProcess, so adding more detailed logging around process start, output, and termination should help identify where things are going wrong.
Modifications:
SWIFTPM_DEBUG_PROCESS_IOenvironment variable to enable low-level I/O thread debugging without interfering with normal observability outputprocessTrackingID(8-character UUID prefix) to uniquely identify each process instance in logs for correlation across multiple concurrent processeslogProcessIODebug()helper that writes directly to stderr when debug mode is enabled, bypassing all handlers to capture issues even when the observability system has problemsResult:
After this change, AsyncProcess will log detailed information about process lifecycle events, including when processes are started, when output is received, and when processes terminate. This should provide better visibility into where hangs may be occurring during dependency resolution.
Users experiencing hangs can now run: