[lldb/test] Enable faulthandler in dotest

Authored by rupprecht on Sep 16 2020, 2:26 PM.


[lldb/test] Enable faulthandler in dotest

Register the faulthandler module so we can see what lldb tests are doing when they misbehave (e.g. run under a test runner that sets a timeout). This will print a stack trace for the following signals:

  • SIGSEGV, SIGFPE, SIGABRT, SIGBUS, and SIGILL (via faulthandler.enable())
  • SIGTERM (via faulthandler.register(SIGTERM)) [This is what our test runners sends when it times out].

The only signal we currently handle is SIGINT (via unittest2.signals.installHandler()) so there should be no overlap added by this patch.

Because this import is not available until python3, and the register() method is not available on Windows, this is enabled defensively.

This should have absolutely no effect when tests are passing (or even normally failing), but can be observed by running this while ninja is running:

kill -s SIGTERM $(ps aux | grep dotest.py | head -1 | awk '{print $2}')

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D87637