[mapserver-dev] python mapscript and msCleanup issues

[Umberto Nicoletti]

On Monday, July 2, 2012, Stephan Meißl wrote:

> Hi Umberto,
>
> many thanks for your help. I tried both suggestions but without an
> optimal result.
>
> Using msIO_resetHandlers() instead of msCleanup() gives me, after using
> a fairly big amount of memory, quite strange results. In fact sometimes
> results from previous requests are present in responses. It seems, that
> not everything gets cleared. Any suggestion how to investigate this?


msIO_resetHandlers should probably be invoked after the response has been
commited, could you take a look at this page:

http://code.google.com/p/modwsgi/wiki/RegisteringCleanupCode

and implement the cleanup hook as described?


>
> Using msIO_getStdoutBufferString() seems to work for text responses only
> but not for images.
>
> Thanks,
> Stephan
>
>
> On Sun, 2012-07-01 at 12:06 +0200, Umberto Nicoletti wrote:
> > Before we turn on debugging mode let's try a couple of simple changes
> > to your script:
> >
> >
> > http://pastebin.ca/2165984
> >
> >
> > I have replaced the call to msCleanup with a call to
> > msIO_resetHandlers which clears all buffers.
> >
> >
> > http://pastebin.ca/2165986
> >
> >
> > same as before but with the buffer accessed as a string rather than a
> > byte array (string is not copied inside mapscript, array is).
> >
> >
> > Let us now how this goes.
> >
> >
> > Umberto
> >
> > On Thu, Jun 28, 2012 at 8:02 PM, Stephan Meißl <stephan at meissl.name>
> > wrote:
> >         Thomas, Umberto,
> >
> >         we created a simple (at least as simple as possible) test
> >         case. Here is
> >         a basic Python script: http://pastebin.ca/2165345 which we
> >         deployed in
> >         Apache using mod_wsgi with this config:
> >         http://pastebin.ca/2165346
> >
> >         There is also a basic mapfile using the "road" data in
> >         "msautotets/wxs"
> >         http://pastebin.ca/2165329 but I suspect you can use whatever
> >         mapfile
> >         you have at hand.
> >
> >         When we issue multiple simultaneous requests e.g. using this
> >         script
> >         http://pastebin.ca/2165348 (note the "&" at the end of the
> >         curl call)
> >         some of the requests result in errors.
> >
> >         Either removing the call to msCleanup() or extending the
> >         Apache config
> >         to limit the number of threads to 1
> >         (http://pastebin.ca/2165347) seems
> >         to resolve the issues but of course with limitations.
> >
> >         Are we missing anything essential? How should we free
> >         request/map
> >         objects without using msCleanup() in Python?
> >
> >         Thanks for any hint,
> >         Stephan
> >
> >
> >         On Thu, 2012-06-28 at 14:15 +0200, Umberto Nicoletti wrote:
> >         > Fabian,
> >         > if you could put together a test case that I can run to
> >         reproduce the
> >         > problem I will take a look into it.
> >         >
> >         >
> >         > Regards,
> >         > Umberto
> >         >
> >         > On Thu, Jun 28, 2012 at 1:44 PM, thomas bonfort
> >         > <thomas.bonfort at gmail.com> wrote:
> >         >         Fabian,
> >         >         can you get a backtrace of the segfaults?
> >         >
> >         >         Aside from that, I would personally refrain from
> >         using threads
> >         >         with
> >         >         mapscript and stick to a prefork mpm in apache to
> >         accomplish
> >         >         this. It
> >         >         is also my understanding that calling m
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