Re: [SOLVED] Re: How to run shell command from response handler? (Apache2 child segmentation fault)

Hello All,

Ok, maybe I'm missing the whole point of this thread, but why is this
solution better than using the built-in perl `date` function?

Personally, I think using the system 'date' function provides too many
variables [read: problems] when attempting cross-platform continuity.

Maybe I have misunderstood the whole point of this thread, but it seems to
me that everyone is over-engineering the problem... (i've only been a Perl
programmer for like three years, so I still have ton's to learn...
hopefully I can learn from this if I'm  way off base)

Thanks,
Jon A

On Tue, Jan 3, 2012 at 8:38 PM, David Booth <[email protected]> wrote:

> Thanks for the suggestion.  I tried it with prefork and the problem
> still occurred.  HOWEVER, I then decided to remove all modules down to a
> minimal example, and discovered that the mere inclusion of the following
> module:
>
>  use Test::MockObject;
>
> was causing the segmentation fault after several successful requests,
> even though no functions whatsoever were called.  Since this appears to
> be a bug in Test::MockObject, I reported the bug here:
> https://rt.cpan.org/Public/Bug/Display.html?id=73723
>
> The bug report shows the exact minimal handler code that I used to
> reproduce the bug.
>
> Best wishes,
> David
>
>
> On Tue, 2012-01-03 at 17:26 -0500, Daniel Risacher wrote:
> > I think I've been bitten by this too, years ago.
> >
> > I *think* I solved it by switching to mpm_prefork, which was
> > unsatisfying, but adequate for my needs.
> >
> > On Tue, Jan 3, 2012 at 5:21 PM, David Booth <[email protected]> wrote:
> > > I tried redirecting stderr to /dev/null and it did not help:
> > > system("date >> $f 2> /dev/null");
> > >
> > > I am using the worker processing model.  Does it work for you (or
> anyone
> > > else) without causing periodic child process segmentation faults?
> > >
> > >
> > > On Tue, 2012-01-03 at 16:29 -0500, Daniel Risacher wrote:
> > >> It's been a while since I looked at doing this, but IIRC it's fairly
> > >> dependent on the processing model that Apache is using.  Are you
> > >> mpm_prefork, or mpm_worker?
> > >>
> > >> Also, I found it was important to redirect stderr to /dev/null:
> > >>
> > >> sub play {
> > >>     system "/usr/bin/xmms -t 2> /dev/null";
> > >> }
> > >>
> > >>
> > >> On Tue, Jan 3, 2012 at 12:48 PM, David Booth <[email protected]>
> wrote:
> > >> > I am trying to run a shell command from a mod_perl2 response
> handler.
> > >> > It works properly for some number of HTTP requests, but sometimes it
> > >> > fails (somewhat randomly) and I see in my Apache2 error log that
> one of
> > >> > the Apache2 child processes has died with a segmentation fault.
> > >> > For example, /var/log/apache2/error.log shows:
> > >> >
> > >> > [Tue Jan 03 12:16:10 2012] [notice] child pid 3538 exit signal
> Segmentation fault (11)
> > >> >
> > >> > Is this normal?  How does one normally run a shell command from a
> > >> > response handler?  I do not want to return the command's output to
> the
> > >> > client.
> > >> >
> > >> > Here is a trivial example response handler that exhibits this
> behavior:
> > >> >
> > >> > sub handler
> > >> > {
> > >> > my $r = shift || die;
> > >> > my $f = $ENV{DOCUMENT_ROOT} . "/date.txt";
> > >> > system("date >> $f");
> > >> > $r->internal_redirect("/date.txt");
> > >> > return Apache2::Const::OK;
> > >> > }
> > >> >
> > >> > Can anyone provide any guidance?  Does this work for you?
> > >> >
> > >> > Note that you may not notice the problem if you don't carefully
> watch
> > >> > the Apache2 error log (e.g., with "tail -f
> /var/log/apache2/error.log"),
> > >> > because Apache2 automatically spawns new children processes as
> needed,
> > >> > and client (such as Firefox or wget, though not curl) seem to
> > >> > automatically re-try the request when it fails, thus giving the
> illusion
> > >> > of succeeding.
> > >> >
> > >> > P.S. I have posted about this on perlmonks, but thus far have not
> found
> > >> > a solution:
> > >> > http://www.perlmonks.org/?node_id=945947
> > >> >
> > >> >
> > >> > --
> > >> > David Booth, Ph.D.
> > >> > http://dbooth.org/
> > >> >
> > >> > Opinions expressed herein are those of the author and do not
> necessarily
> > >> > reflect those of his employer.
> > >> >
> > >>
> > >>
> > >
> > > --
> > > David Booth, Ph.D.
> > > http://dbooth.org/
> > >
> > > Opinions expressed herein are those of the author and do not
> necessarily
> > > reflect those of his employer.
> > >
> >
> >
>
> --
> David Booth, Ph.D.
> http://dbooth.org/
>
> Opinions expressed herein are those of the author and do not necessarily
> reflect those of his employer.
>
>


-- 
Best Regards,
Jonathan David

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