Locating infinite loops

[Matt Sergeant <ms...@startechgroup.co.uk>]

I have an error on my server that I think is caused by an infinite loop in
perl code [*]. Does anyone have a reliable way to detect where this is
happening on a server with lots of code?

Matt.
-- 
<:->Get a smart net</:->

[*] In case anyone was wondering, this is probably why you can't get to
axkit.org at the moment, and my car is in the garage, so I can't get home to
login and kill the rogue process, and ssh won't let me in due to timeouts.
Yes, I need Apache::Watchdog, I know.

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Re: Locating infinite loops

[Jeremy Howard <jh...@fastmail.fm>]

Matt Sergeant asked:
> I have an error on my server that I think is caused by an infinite loop in
> perl code [*]. Does anyone have a reliable way to detect where this is
> happening on a server with lots of code?
>
----
  $SIG{ALRM} = sub {
    Carp::confess("Got Apache::Event ALRM");
  };
  alarm(300);
----
Replacing 300 with some amount which any process should finish in.

Not elegent, but it seems to work. For instance, this:
----
use Carp;

$SIG{ALRM} = sub {
Carp::confess("Got Apache::Event ALRM");
};
alarm(3);
temp();
sub temp {
  sleep(5);
}
----

...gives this result:
----
Got Apache::Event ALRM at testal.pl line 4
        main::__ANON__('ALRM') called at testal.pl line 9
        main::temp() called at testal.pl line 7
----

...which even shows which line Perl was up to when the SIGALRM was called
(line 9 in this case).

Re: Locating infinite loops

[Stas Bekman <st...@stason.org>]

Matt Sergeant wrote:

> I have an error on my server that I think is caused by an infinite loop in
> perl code [*]. Does anyone have a reliable way to detect where this is
> happening on a server with lots of code?


http://perl.apache.org/guide/debug.html#Using_the_Perl_Trace

-- 


_____________________________________________________________________
Stas Bekman             JAm_pH      --   Just Another mod_perl Hacker
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