Using multiprocessing from a Windows service

Mark Hammond skippy.hammond at
Fri Feb 6 05:26:08 CET 2009

On 6/02/2009 2:50 PM, Mark Hammond wrote:
> On 6/02/2009 11:37 AM, Volodya wrote:
>> Hi all,
>> I think I've found a small bug with multiprocessing package on
>> Windows.
> I'd actually argue its a bug in pythonservice.exe - it should set
> sys.argv[] to resemble a normal python process with argv[0] being the
> script. I'll fix it...

Actually it appears I spoke too soon:

* A bug in pywin32 exists such that when you use 'debug' on a service, 
the argv reflected the full argv of the application, including the 
'-debug' portion of the command-line.  However, even if that is fixed, 
the next argument is actually the name of the service (as declared in 
the .py file for the service), not the .py module itself.  Thus, I could 
make argv a little more sane in this case, but still the initial problem 
would remain as argv[0] would still not be a .py file.

* When the service is started by windows itself, there are usually zero 
additional command-line arguments.  If there *are* arguments, they are 
likely to be the string the user entered via control panel as a special 
case (Windows doesn't actually remember service args - they are used 
once and discarded).  It is important we continue to expose whatever 
argv we actually got from Windows to the service code.

So unfortunately I don't think I can change pythonservice to resolve the 
issue you reported.



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