seg fault - how to track down cause!

[bruce]

Hey guys..

Running a test parent php app that's a long running app. It spins out
test child apps via the "system" call periodically. On an intermittent
basis, the parent php app dies, and I get a segmentation fault error.

Any thoughts/pointers on what I can setup from an OS perspective to
allow me to track down exactly what's causing this to happen..

Thanks

[Jack Craig]

i like strace

if you dont have it, yum install it.

using man page, see launching parent pid  under strace with follow option.

in the verbose output, focus on system call activity (& parms) for failing
pid  procs.

HTH, jackc...

On Thu, Aug 7, 2014 at 5:01 PM, bruce  wrote:
> Hey guys..
>
> Running a test parent php app that's a long running app. It spins out
> test child apps via the "system" call periodically. On an intermittent
> basis, the parent php app dies, and I get a segmentation fault error.
>
> Any thoughts/pointers on what I can setup from an OS perspective to
> allow me to track down exactly what's causing this to happen..
> Thanks
>
> users mailing list
> [e-mail]
> To unsubscribe or change subscription options:
> https://admin.fedoraproject.org/mailman/listinfo/users
> Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
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> Have a question? Ask away: http://ask.fedoraproject.org

[bruce]

can you run strace on an app that's going to run for 2-3 solid days??

On Thu, Aug 7, 2014 at 8:41 PM, Jack Craig  wrote:
> i like strace
>
> if you dont have it, yum install it.
>
> using man page, see launching parent pid  under strace with follow option.
>
> in the verbose output, focus on system call activity (& parms) for failing
> pid  procs.
>
> HTH, jackc...
>
> On Thu, Aug 7, 2014 at 5:01 PM, bruce  wrote:
> > Hey guys..
> >
> > Running a test parent php app that's a long running app. It spins out
> > test child apps via the "system" call periodically. On an intermittent
> > basis, the parent php app dies, and I get a segmentation fault error.
> >
> > Any thoughts/pointers on what I can setup from an OS perspective to
> > allow me to track down exactly what's causing this to happen..
> > Thanks
> >
> > users mailing list
> > [e-mail]
> > To unsubscribe or change subscription options:
> > https://admin.fedoraproject.org/mailman/listinfo/users
> > Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
> > Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
> > Have a question? Ask away: http://ask.fedoraproject.org
>
> --
> users mailing list
> [e-mail]
> To unsubscribe or change subscription options:
> https://admin.fedoraproject.org/mailman/listinfo/users
> Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
> Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
> Have a question? Ask away: http://ask.fedoraproject.org

[Jack Craig]

yes!  use ps *** to get parent pid to follow, then i think the chant is
something like,

strace -f -p <pid>

note, a lot of system call info gets dumped, but IMHO, the needle is in
that haystack!

you might want to log output to a file, ...

also, i loved to find a failing clue and then pipe strace -f ... | grep
<myclue>

but i digress,...

Good Luck!! [?]

hth, ...

On Thu, Aug 7, 2014 at 5:43 PM, bruce  wrote:
> can you run strace on an app that's going to run for 2-3 solid days??
>
> On Thu, Aug 7, 2014 at 8:41 PM, Jack Craig 
> wrote:
> > i like strace
> >
> > if you dont have it, yum install it.
> >
> > using man page, see launching parent pid  under strace with follow
>
> option.
> > in the verbose output, focus on system call activity (& parms) for
>
> failing
> > pid  procs.
> >
> > HTH, jackc...
> >
> > On Thu, Aug 7, 2014 at 5:01 PM, bruce  wrote:
> > > Hey guys..
> > >
> > > Running a test parent php app that's a long running app. It spins out
> > > test child apps via the "system" call periodically. On an intermittent
> > > basis, the parent php app dies, and I get a segmentation fault error.
> > >
> > > Any thoughts/pointers on what I can setup from an OS perspective to
> > > allow me to track down exactly what's causing this to happen..
> > > Thanks
> > >
> > > users mailing list
> > > [e-mail]
> > > To unsubscribe or change subscription options:
> > > https://admin.fedoraproject.org/mailman/listinfo/users
> > > Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
> > > Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
> > > Have a question? Ask away: http://ask.fedoraproject.org
> >
> > --
> > users mailing list
> > [e-mail]
> > To unsubscribe or change subscription options:
> > https://admin.fedoraproject.org/mailman/listinfo/users
> > Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
> > Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
> > Have a question? Ask away: http://ask.fedoraproject.org
>
> --
> users mailing list
> [e-mail]
> To unsubscribe or change subscription options:
> https://admin.fedoraproject.org/mailman/listinfo/users
> Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
> Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
> Have a question? Ask away: http://ask.fedoraproject.org

[Patrick O'Callaghan]

On Thu, 2014-08-07 at 17:51 -0700, Jack Craig wrote:
> yes!  use ps *** to get parent pid to follow, then i think the chant
> is
> something like,
>
> strace -f -p <pid>
>
> note, a lot of system call info gets dumped, but IMHO, the needle is
> in
> that haystack!
>
> you might want to log output to a file, ...
>
> also, i loved to find a failing clue and then pipe strace -f ... |
> grep
>
> <myclue>

Or you can attach a gdb instance to it and watch the segfault happening,
get a backtrace etc. That's what debuggers are for.

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poc