[python-win32] Silent crashes in calls to a COM object in Python

[Deniz Pelvan]

Hello again Mark,I am not sure what you mean by direct call? The COM object is loaded inproc (i.e. the COM object is not in a service proc and I don't see any temp processes created by python or pywin32) but I thought you were using the IDispatch interface to find and load the dll & object rather than a direct interface call (which would require type library etc. knowledge). As for the test app, it is not using the IDispatch interface so the IDispatch might be causing trouble.The prompt I mentioned is the Python interpreter prompt, btw. I will try to dig deeper into the python interpreter with the debugger and see if there is anything else I can catch. Thanks for the helpDeniz
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> Date: Tue, 24 Apr 2012 15:07:39 +1000
> From: mhammond at skippinet.com.au
> To: i_pelvan at hotmail.com
> CC: python-win32 at python.org
> Subject: Re: [python-win32] Silent crashes in calls to a COM object in Python
>
> On 24/04/2012 2:55 PM, Deniz Pelvan wrote:
> > Hello Mark,
> > As I mentioned, I ran my COM interface with another Win32 test app under
> > a MSVC debugger for hours without any problem. I attached a debugger to
> > the Python process but with Python, the script goes all the way to that
> > call, waits about a minute in that call and then without throwing any
> > exceptions or errors, the script stops running (i.e. the next line in
> > the script never gets called) and Python drops back to the prompt.
> > Nothing gets caught by the debugger.
>
> I'm not quite with you here - I assume Python is using an inproc version
> of your object, so the COM call made by Python is actually a direct call
> into your object. In that scenario, I can't see how execution will
> return to Python without your object actually returning.
>
> If it is not an inproc object, then it may be that the default COM
> marshaller is indeed timing out, but I'm not familiar with that or under
> what circumstances this will happen but it might be worth looking at
> what "apartment" things are running in, and/or any other differences
> between the environment your test app runs under and that of Python.
>
> I'm also not sure what prompt you are referring to - the Python prompt
> or a cmdline prompt? Either way, with the debugger you should be able
> to see the call to IDispatch::Invoke made by Python (hrm - but sadly you
> will probably need to build pywin32 yourself so you get debugging
> symbols). If you can see that call to Invoke(), you should be able to
> determine if that call never returns (in which case it is almost
> certainly the marshaller) or if it returns with an error code or 0.
>
> There isn't much else in Python or pywin32 that can help - depending on
> how you construct the COM object, there are one or 2 places where the
> Python code calls "dispatchobject.Invoke()" (or
> dispatchobject.InvokeTypes()) which is basically a direct call from the
> interpreter into win32com/src/PyIDispatch.cpp - the debugger is the best
> tool for that...
>
> Mark
>
>
> > I was wondering if there are any options either in the Python
> > interpreter or in pywin32 (or maybe a debug version) that can show what
> > is happening internally, especially over the COM dispatch...
> > Thanks in advance
> > Deniz
> >
> >
> > > Date: Tue, 24 Apr 2012 11:08:12 +1000
> > > From: skippy.hammond at gmail.com
> > > To: i_pelvan at hotmail.com
> > > CC: python-win32 at python.org
> > > Subject: Re: [python-win32] Silent crashes in calls to a COM object
> > in Python
> > >
> > > Python and pywin32 don't impose any time limits for timeouts and I can't
> > > think of what could cause this other than (say) an exception handler in
> > > your script that ignores exceptions and terminates the process. Even if
> > > Python actually crashed I'd expect Windows to show the "app crashed"
> > > dialog. If you have MSVC you could try running the python process under
> > > it to see if it reports anything strange.
> > >
> > > Mark
> > >
> > > On 24/04/2012 8:09 AM, Deniz Pelvan wrote:
> > > >
> > > > Hello guys,I am having trouble with the Python interpreter crashing
> > > > silently (no exceptions or errors thrown) when I make a call to a
> > > > very CPU-intensive method in my COM/ATL component using Pywin32. The
> > > > method is an FFT analysis for audio files and hits about 25% CPU on a
> > > > single core and runs for about 1 minutes. I have tested the COM
> > > > method intensively via normal win32 applications and there are no
> > > > problems with it (I can run the same method over and over again 1000s
> > > > of times in a win32 app).- Also the same Python script (with a call
> > > > to this COM method) will run successfully on different machines and
> > > > will fail at the same machine only randomly (i.e. on some machines,
> > > > it never fails, while on others, it has ~50% failure rate). - This
> > > > specific method is the most CPU-intensive one in the COM component
> > > > and other methods do not fail on any of the machines. Because of
> > > > this, I think the problem might have something to do with either the
> > > > CPU usage or a timeout feature on Python or pywin32. Are there any
> > > > tools that would help me narrow down the cause or maybe increase the
> > > > CPU/time limits for Python/PyWin32? I haven't seen anything in the
> > > > documentation that'd help.Thanks in advanceDeniz Pelvan
> > > > _______________________________________________ python-win32 mailing
> > > > list python-win32 at python.org
> > > > http://mail.python.org/mailman/listinfo/python-win32
> > > >
> > >
> > >
>
>