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Differential D4870

showstack: also handle SIGALRM
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Authored by durin42 on Oct 3 2018, 4:13 PM.

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rHGacf5dbe39478: showstack: also handle SIGALRM
Summary

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?

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durin42 created this revision.Oct 3 2018, 4:13 PM
Closed by commit rHGacf5dbe39478: showstack: also handle SIGALRM (authored by durin42). · Explain WhyOct 4 2018, 8:31 AM
This revision was automatically updated to reflect the committed changes.

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Mcontrib/showstack.py (8 lines)

Diff 11653

contrib/showstack.py

# showstack.py - extension to dump a Python stack trace on signal # showstack.py - extension to dump a Python stack trace on signal
# #
# binds to both SIGQUIT (Ctrl-\) and SIGINFO (Ctrl-T on BSDs) # binds to both SIGQUIT (Ctrl-\) and SIGINFO (Ctrl-T on BSDs)
"""dump stack trace when receiving SIGQUIT (Ctrl-\) and SIGINFO (Ctrl-T on BSDs) """dump stack trace when receiving SIGQUIT (Ctrl-\) and SIGINFO (Ctrl-T on BSDs)
""" """
from __future__ import absolute_import from __future__ import absolute_import, print_function
import signal import signal
import sys import sys
import traceback import traceback
def sigshow(*args): def sigshow(*args):
sys.stderr.write("\n") sys.stderr.write("\n")
traceback.print_stack(args[1], limit=10, file=sys.stderr) traceback.print_stack(args[1], limit=10, file=sys.stderr)
sys.stderr.write("----\n") sys.stderr.write("----\n")
def sigexit(*args):
sigshow(*args)
print('alarm!')
sys.exit(1)
def extsetup(ui): def extsetup(ui):
signal.signal(signal.SIGQUIT, sigshow) signal.signal(signal.SIGQUIT, sigshow)
signal.signal(signal.SIGALRM, sigexit)
try: try:
signal.signal(signal.SIGINFO, sigshow) signal.signal(signal.SIGINFO, sigshow)
except AttributeError: except AttributeError:
pass pass