[Twisted-Python] can I detect a child stopped?

exarkun at twistedmatrix.com exarkun at twistedmatrix.com
Sun Dec 5 02:29:05 EST 2010

On 4 Dec, 07:10 pm, ndbecker2 at gmail.com wrote:
>exarkun at twistedmatrix.com wrote:
>>On 03:47 pm, ndbecker2 at gmail.com wrote:
>>>Using processProtocol.  If a child is stopped (e.g., by SIGSTOP), is
>>>some way to detect this?
>>The parent will get a SIGCHLD when the child gets SIGSTOP or SIGCONT.
>>Using sigaction, you can learn which process was affected, and in what
>>way.  We don't have a sigaction wrapper that provides this
>>functionality, though (the stdlib signal.signal actually wraps
>>sigaction, but it doesn't expose any more functionality than you get
>>from signal(2)).
>Didn't twisted already install it's own signal handler for SIGCHLD?  So
>you're suggesting I can chain my own, which then calls the one 
>installed by

No, at least not with `signal.signal`, because the necessary information 
isn't exposed by Python.  You need to get the siginfo_t that 
sigaction(2) provides, but isn't exposed to Python.

If there were a module exposing that functionality, then you could 
perhaps work something out.  If such a module were generally available, 
Twisted could even try using it to provide this functionality out of the 


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