Bus Error from threading IO::Socket

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

I came across this script I have been using for handling multiple socket connections. I am new to IO::Socket in general. When a client disconnects, the server ends with a "Bus Error". I am doing this on OSX 10.5.1. Any ideas?

#!/usr/bin/perl
use strict;
use warnings;
use IO::Socket;
use threads;

system("clear");
print "Server Listening on tcp/7890\n";

my $lsn = new IO::Socket::INET(
   Listen    => '10',
   LocalPort => '7890',
   Proto     => 'tcp',
   ReUse     => 1,
) or die $!;

sub do_stuff {
   my $sock = shift;
   print "Client connected\n";

   while( my $input = <$sock> ) {
      chomp( $input );
      print "$input\n";
   }
   print "Client disconnected\n";
}

threads->create( \&do_stuff, $lsn->accept, )->detach while 1;
[download]

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Re: Bus Error from threading IO::Socket by snoopy (Curate) on Aug 12, 2008 at 02:35 UTC
I also get the bus error on OSX 10.5.1. Runs fine for me on Debian. I notice that the bus error goes away when you don't `detach` the thread, ie, works fine when I change the last line to: `threads->create( \&do_stuff, $lsn->accept, ) while 1;` [download] Detached threads seem to be a contributing factor.	[reply] [d/l]
Re: Bus Error from threading IO::Socket by jethro (Monsignor) on Aug 12, 2008 at 02:10 UTC
Just tested the script on my linux box and it worked flawlessly. Is perl included with Mac OS or did you install it?	[reply]
Re: Bus Error from threading IO::Socket by Perlbotics (Archbishop) on Aug 12, 2008 at 10:55 UTC
When the client disconnects, the process usually receives a SIGPIPE signal. That might also contribute to your problem when the corresponding (unaccessible?) handler is called. You might want to install a signal handler to further investigate this? Do you see the "Client disconnected" message? Please add `$\|=1;` early to `do_stuff` so buffering will not swallow this message. Another Idea: SIGBUS is usually caused by a misaligned memory access. Thus, a change of your dynamically loaded libraries might have caused that (since Perl was compiled). Did you modify `LD_LIBRARY_PATH` lately? `ldd` your_perl_executable together with `perl -V \| egrep thread` might shed some light on this issue.	[reply] [d/l] [select]
Re: Bus Error from threading IO::Socket by BrowserUk (Patriarch) on Aug 12, 2008 at 17:09 UTC
Personally, I'd re-cast your main loop as: `while( 1 ) { my $c = $lsn->accept; print "Client connected: $c"; threads->create( \&do_stuff, $c )->detach; undef $c; }` [download] Whether that will make the slightest difference on your platform/versions I cannot test, but I have a hunch it might. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply] [d/l]
Re: Bus Error from threading IO::Socket by zentara (Cardinal) on Aug 12, 2008 at 16:43 UTC
*Detached threads seem to be a contributing factor.* A detached thread must return, and I'm guessing on your platform, the socket isn't closing itself automatically. Maybe try something like this: `sub do_stuff { my $sock = shift; print "Client connected\n"; while( my $input = <$sock> ) { chomp( $input ); print "$input\n"; } print "Client disconnected\n"; $sock->close; #or close($sock); return; }` [download] I'm not really a human, but I play one on earth Remember How Lucky You Are	[reply] [d/l]