http://qs1969.pair.com?node_id=220599

jhanna has asked for the wisdom of the Perl Monks concerning the following question:

This is a follow up to node Mysterious script crash in win2k

sub mlog {
 my $fh=shift;
 d(34);
 my $m=localtime();
 $m=~s/^... (...) +(\d+) (\S+) ..(..)/$1-$2-$4 $3/;
 $m.= " $Con{$fh}->{ip} <$Con{$fh}->{mailfrom}>" if $fh && $Con{$fh};
 $m.= " $_[0]\n";
 print $m unless $silent;
 print DEBUG  $m;
 if($logfile && open(LOG,">>$logfile")) {print LOG $m; close LOG;}
}

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I localized the last crash to this subroutine. d(34) printed 34 in the debug file, but the $m never appeared on the console, nor in the DEBUG log file (which is unbuffered), neither in the LOG file.

This means the program crashed inside localtime(), or doing a s/// regexp replace, or concatenating to a string ($m). The $_[0] parameter that was passed in was a string constant: 'local or whitelisted', and was called this way:

  if(onwhitelist($fh,$this->{header})) {
   setmaillog(0,$fh);
   isnotspam($fh);
   mlog($fh,'local or whitelisted');
  }

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The setmaillog and isnotspam functions operated correctly and also affirm that $this is not corrupted.

Help! Something I'm doing is corrupting perl internally, and I don't know how to find that kind of bug!

john

P.S. Here's my perl's version:

This is perl, v5.6.1 built for MSWin32-x86-multi-thread
(with 1 registered patch, see perl -V for more detail)

Copyright 1987-2001, Larry Wall

Binary build 630 provided by ActiveState Tool Corp. http://www.ActiveState.com
Built 20:29:41 Oct 31 2001

Replies are listed 'Best First'.
Re: still have a mysterious crash
by Thelonius (Priest) on Dec 17, 2002 at 19:07 UTC
    I localized the last crash to this subroutine. d(34) printed 34 in the debug file, but the $m never appeared on the console, nor in the DEBUG log file (which is unbuffered), neither in the LOG file.

    This means the program crashed inside localtime(), or doing a s/// regexp replace, or concatenating to a string ($m). The $_[0] parameter that was passed in was a string constant: 'local or whitelisted', and was called this way:

    And you stopped localizing the error because ...?

    print DEBUG "Line ", __LINE__, "\n"; before each line at the very least.

    You can also 

    print DEBUG "\$fh = $fh\n";
print DEBUG "\$Con{\$fh} = $Con{$fh}\n";
print DEBUG "\$Con{\$fh}->{ip} = $Con{$fh}->{ip}\n";
print DEBUG "\$Con{\$fh}->{mailfrom} = $Con{$fh}->{mailfrom}\n";

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[reply]
[d/l]
[select]
      And I stopped localizing because the thing takes 2 - 14 hours to crash (unpredictably). I put in more d() lines, but have to wait for it to crash again before I can get closer. Besides, if it's a perl internal problem it'll pick another random place to die next time.

      j

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Re: still have a mysterious crash
by dingus (Friar) on Dec 17, 2002 at 19:08 UTC
    This is probably not the solution. But it will change the localtime line and remove the s/// one. I don't say its better but it might throw some light on what's happening. 
     my ($sec,$min,$hour,$mday,$mon,$year) = localtime();
 my $m = ('Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct',
+'Nov','Dec')[$mon].
   "-$mday-".substr($year,-2).sprintf(' %02d:%02d:%02d', $hour,$min,$s
+ec);
 $m.= " $Con{$fh}->{ip} <$Con{$fh}->{mailfrom}>" if $fh && $Con{$fh};
 $m.= " $_[0]\n";
 print $m unless $silent;
 print DEBUG  $m;

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    Yes it is a strike at semi-random. What I guess may happen is that the problem now moves to a completely differet place. If so I suspect you may be looking at a weird memory leak kind of error. However I did get a very very weird crash the first time I ran your 2 lines in a CGI script - it broke the webserver! Needless to say this hasn't happened since.

    Dingus

    Enter any 47-digit prime number to continue.
[reply]
[d/l]
      I thought about messing with that line as well, but it baffles me why it would work 99.99% of the time and then fail.

      Curious that it broke your server. Maybe I'm not insane!

      j

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