i#7955: Fix sigmask test signal race#7956
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Blocks the SIGALRM in the main thread to prevent a case where the helper thread runs quickly and sends the signal before the main thread has had a change to block in sigsuspend. SIGALRM is unblocked by the helper thread so it can receive the itimer signals. This fixes linux.sigmask and linux.sigmask-noalarm in local runs with 100x iterations. Adds a TODO for an edge case where we don't want DR to execute the app sigsuspend if a newly or previously unblocked signal is already pending Issue: #7955
abhinav92003
changed the title
derekbruening
approved these changes
Jun 19, 2026
Without blocking the SIGARLM (before this PR), the test app would sometimes have should_exit=true before even reaching the while loop, so would not execute the sigsuspend even one time. Add a check that it does.
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Blocks the SIGALRM in the main thread to prevent a case where the helper thread runs quickly and sends the signal before the main thread has had a chance to block in sigsuspend; the sigsuspend unblocks SIGALRM. SIGALRM is also unblocked by the helper thread so it can receive the itimer signals.
This fixes linux.sigmask and linux.sigmask-noalarm in local runs with 100x iterations, which would previously hang sometimes.
Adds a TODO for an edge case where we don't want DR to execute the app sigsuspend if a newly or previously unblocked signal is already pending. This is fixed by the subsequent PR #7958.
Issue: #7955