threading.Condition.wait() is not catching SIGTERM
sangeeth.saravanaraj at gmail.com
Fri Jul 4 02:48:00 CEST 2014
On 04-Jul-2014, at 1:43 am, Ned Deily <nad at acm.org> wrote:
> In article <17F05A1B-44C8-4F25-AFE9-5DBCFFB9982B at gmail.com>,
>> I have the following code which when executed waits to be interrupted by
>> SIGINT, SIGTERM or SIGQUIT. When an object is initialized, it creates a
>> threading.Condition() and acquires() it! The program then registers the
>> signal handlers where notify() and release() is called when the above
>> mentioned signals are received. After registering the signal handlers, it
>> calls wait() on the condition variable and block.
>> When I tried to stop the program with Ctrl-C, its did not respond. IOW, the
>> _signal_handler() method did not get called.
> I'm not sure what you are trying to do but your test case seems flawed.
> threading.Condition is designed to be used with multiple threads but
> your test doesn't actually use threads. If you run your test with a
> reasonably current Python 3 (after changing print to print()), you can
> see that it fails (and why it fails) when interrupting with Ctrl-C:
> Waiting to be interrupted!
> ^CReceived terminate request - signal = 2
> Traceback (most recent call last):
> File "b.py", line 30, in <module>
> File "b.py", line 27, in main
> File "b.py", line 22, in register_and_wait
> self._termination_signal.wait() # control blocks here!
> g.py", line 289, in wait
> File "b.py", line 13, in _signal_handler
> g.py", line 339, in notify
> raise RuntimeError("cannot notify on un-acquired lock")
> RuntimeError: cannot notify on un-acquired lock
> After a quick glance, I'm not sure why Python 2.7 is behaving
> differently, e.g. not raising an error, since both versions of
> Condition.notify have the same test so the difference is elsewhere.
> Feel free to open an issue for not catching the error in 2.7 but you
Ned, thanks for the explanation.
I have filed http://bugs.python.org/issue21913 to explore further on this issue.
> should rethink what you are trying to do here.
> Ned Deily,
> nad at acm.org
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