[Melbourne-pm] Finding "Out of memory!"

[Bradley Dean]

Yes - that's certainly a safer approach. In fact I've found that what
worked for me in my example code was version sensitive.

On the system I started with the last system call was an mmap2 with a
ENOMEM error and this is what I found when checking $!. I then tested
this on a different system and discovered that after the mmap2 failed
(and before my perl code had a chance to look at $!) a bunch of
rt_sigaction systems calls happened and one of those failed with EINVAL
so there was no ENOMEM to find.

I feel there's a hack with a wrapper script which greps for "Out of
memory!" on STDERR coming my way as the exit code doesn't tell me
anything useful either.

Cheerio,

 Brad

On Fri, Oct 10, 2014, at 10:37, Toby Wintermute wrote:
> I really don't think this approach is going to pay dividends.
> When you're hitting out of memory conditions in Perl, it's usually
> game over. In some languages you could code up something that runs
> without using any more memory, as a handler, but you don't have that
> level of control in Perl.
> 
> I'd look at wrapping your Perl script in another program - maybe just
> a bash or even another Perl script - that waits for it to exit, and
> then checks to see if it exited normally or with an error code.
> 
> On 3 October 2014 11:54, Bradley Dean <bjdean at bjdean.id.au> wrote:
> > Greetings folks,
> >
> > While looking at a problem where a variety of scripts might develop a
> > memory leak and fatally terminate with "Out of memory!" I'm trying to
> > work out if this seemingly simple code is in fact too simple:
> >
> > package NotifyOnOutOfMemory;
> > use Errno;
> > END {
> >     # If the last errno indicates out of memory perl will now be
> >     # terminating with "Out of memory!" so tell me about it.
> >     if ( $! == Errno::ENOMEM ) {
> >         # Do some low-memory thing that tells me a process has died due
> >         to memory exhaustion
> >         # eg. touch /path/to/some/file
> >         #    or - exec("/path/to/script/which/emails/or/logs $$ $0
> >         $someOtherDetail")
> >      }
> > }
> > 1;
> >
> > Which would give me a drop in module for scripts with this problem.
> >
> > What am I missing? :)
> >
> > Cheerio,
> >
> >  Brad
> >
> > --
> > Bradley Dean
> > Email: bjdean at bjdean.id.au Skype: skype at bjdean.id.au
> > Mobile(Aus): +61-413014395 WWW: http://bjdean.id.au/
> > _______________________________________________
> > Melbourne-pm mailing list
> > Melbourne-pm at pm.org
> > http://mail.pm.org/mailman/listinfo/melbourne-pm
> 
> 
> 
> -- 
> Turning and turning in the widening gyre
> The falcon cannot hear the falconer
> Things fall apart; the center cannot hold
> Mere anarchy is loosed upon the world


-- 
Bradley Dean
Email: bjdean at bjdean.id.au Skype: skype at bjdean.id.au
Mobile(Aus): +61-413014395 WWW: http://bjdean.id.au/