`joern` and `joern-parse` are shell scripts that launch a JVM as a separate
process. `subprocess.run(timeout=)` kills the script and leaves the JVM
resident, holding its heap, indefinitely. Every `query_failed: timeout` leaked
about a gigabyte.
Found by running out of memory. After a day of 300s and 2,400s taint timeouts,
four orphaned JVMs -- three hours old, ~2GB between them -- were still resident
on a 7GB machine, and background tasks started being killed. On a CI runner
doing several scans in sequence this is an OOM rather than a degradation, and
it would present as "the scan needs more memory", which is the wrong lesson
entirely: the scan's own peak is a flat ~1.5GB whether its query runs for five
minutes or forty.
The command now starts in its own session, and a timeout SIGTERMs the process
group and SIGKILLs what survives. An injected test runner is left alone,
because those spawn nothing.
Tested with a real shell script that backgrounds a child, since the bug is
specifically about grandchildren -- and the test reaps that child itself if the
assertion fails, rather than leaking the process it is complaining about.
855 tests pass.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG
