fix: sweep the child's process group after every phase - #650
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ykhrustalev wants to merge 2 commits into
Open
ykhrustalev wants to merge 2 commits into
ykhrustalev wants to merge 2 commits into
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On a timeout, terminate_child() sent one SIGTERM and then blocked in wait() with no bound. A cargo process that ignores the signal, or that has been stopped and so never receives it, hung the whole run at that point. Wait only for a short grace period, then SIGKILL the process group. This needs a second signal, so the errno handling moves into a signal_group() helper rather than being duplicated.
Tests can leave processes running after they exit: a helper a test spawned and forgot, or a test binary that was never reaped. Until now cargo-mutants only signalled the child's process group on a timeout, so on a normal exit those processes survived and kept allocating while later mutants were tested, in a window where no cargo phase is running at all. Sweep the group in the process layer, so every phase gets it: once the direct child exits with any status, SIGTERM the group, wait a bounded grace period, then SIGKILL whatever is left. What was reaped goes into the scenario log, and the pids into the debug log, enumerated from /proc on Linux. Windows has no process groups and the job object equivalent is out of scope, so the sweep is a no-op there.
This was referenced Sep 16, 2026
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Problem
Tests can leave processes running after they exit — a helper a test spawned and forgot, or a test binary that was never reaped. The child's process group was only signalled on a timeout, so on a normal exit those survived and kept allocating while later mutants were tested, in a window where no cargo phase was running at all.
Solution
SIGTERM, a bounded grace period, thenSIGKILL./procon Linux) at debug level.killpg(…, 0)rather than a/procwalk.Testing
spawns_background_childtree: its test leavessleep 300running and records the pid; the integration test probes the pid afterwards and checks every mutant's verdict is unchanged. Fails againstmain.Stacked on #648; only the last commit is new here. Split out of #647 as requested.