view CONTRIBUTING @ 40036:acf5dbe39478

showstack: also handle SIGALRM

This is looking *very* handy when debugging mysterious hangs in a
test: you can wrap a hanging invocation in

  `perl -e 'alarm shift @ARGV; exec @ARGV' 1`

for example, a hanging `hg pull` becomes

  `perl -e 'alarm shift @ARGV; exec @ARGV' 1 hg pull`

where the `1` is the timeout in seconds before the process will be hit
with SIGALRM. After making that edit to the test file, you can then
use --extra-config-opt on run-tests.py to globaly enable showstack
during the test run, so you'll get full stack traces as you force your
hg to exit.

I wonder (but only a little, not enough to take action just yet) if we
should wire up some scaffolding in run-tests itself to automatically
wrap all commands in alarm(3) somehow to avoid hangs in the future?

Differential Revision: https://phab.mercurial-scm.org/D4870

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