[Python-Dev] Functionality in subprocess.Popen.terminate()

Eric Pruitt eric.pruitt at gmail.com
Tue Aug 4 17:01:57 CEST 2009

On Tue, Aug 4, 2009 at 04:27, Nick Coghlan<ncoghlan at gmail.com> wrote:
> Eric Pruitt wrote:
>> In my GSoC project, I have implemented asnychronous I/O in
>> subprocess.Popen. Since the read/write operations are asynchronous, the
>> program may have already exited by the time one calls the asyncread
>> function I have implemented. While it returns the data just fine, I have
>> come across an issue with the TerminateProcess function in Windows: if
>> the program has already exited, when subprocess.Popen.Terminate calls
>> the Windows built-in "TerminateProcess" function, an "access denied"
>> error will occur. Should I just make it so that this exception is simply
>> ignored or perform some kind of check to see if the process exists
>> beforehand? If the latter, I have been unable to find a way to do so, to
>> my liking at least. The solutions I saw would require code that seems a
>> bit excessive to me.
> I'm pretty sure we already ignore some spurious error messages in cases
> like calling flush() in file.close(). I would suggest checking what the
> io module does in such cases and see what kind of precedent it sets.
> Cheers,
> Nick.
> --
> Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
> ---------------------------------------------------------------

Sounds good enough to me but I was wondering if it might be a good
idea to add a function like "pidinuse" to subprocess as a whole that
would determine if a process ID was being used and return a simple
boolean value. I came across a number of people searching for a way to
determine if a PID was running (Google "python check if pid exists")
so it seems like the implemented functionality would be of use to the
community as a whole, not just my wrapper class.


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