Fix start test program race condition #33
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icemac
reviewed
Mar 14, 2024
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Thank you for tackling this issue. |
dataflake
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Mar 14, 2024
Co-authored-by: Michael Howitz <icemac@gmx.net>
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Fixes #32.
#32 is caused by a race condition between the
SIGCHLDsignal handler and thewaitinsubprocess.callused to start thestart-test-program. If the signal handler is activated before thewaitcall, thewaitcan no longer determine the process' exit status and (erroneously) claims the process exited successfully. In those cases, the start test ends prematurely.This PR avoids the problem by letting the
SIGCHLDhandler record the exit status for unknown processes. If the start test gets a successful exit fromsubprocess, it verifies that theSIGCHLDhandler has not recorded a contradicting exit status.The race is very rare. To provoke it (for testing), you can uncomment the line
import time; time.sleep(0.01)inzdaemon.zdrun.Subprocess.test.