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Date: Thu, 20 Jul 2006 22:32:09 +0200 (CEST)
Subject: Re: Perl failure
From: "Bengt-Arne Fjellner" <Bengt-Arne DOT Fjellner AT ltu DOT se>
To: cygwin AT cygwin DOT com
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Christopher Faylor skrev:
> On Wed, Jul 19, 2006 at 12:08:24PM +0200, Corinna Vinschen wrote:
>>On Jul 18 17:45, Bruce Dobrin wrote:
>>> Hi,
>>> I stripped down the code to a small testable bit.  The problem seems to
>>> occur when I reach 256 forks on a cygwin1.5.18 or 19 but not on my
>>> cygwin1.5.5. win2k system.  The original code give the forked process
>>> time to finish,  but it still looks like it eats it after about 256
>>> iterations  ( it actually failed between 259 and 252 iterations,  but
>>> it's pretty complicated so I'm not sure what else was happening).
>>>
>>> Here is my test code:
>>> dobrin AT tiburon:/tmp> cat test8.pl
>>> ################
>>> #!/usr/bin/perl -w
>>>
>>> use strict;
>>> my $pid;
>>>
>>> foreach my $incr (`seq 1 1 800`) {
>>>
>>>                     unless (defined ($pid = fork)) {
>>>                          die " cannot fork $!";
>>>                      }
>>>                     unless ($pid) {
>>>                       print " the sequence is $incr \n";
>>>                       exit;
>>>                     }
>>>              print "pid is $pid\n";
>>>            }
>>>
>>> ###############
>>>
>>> The error here is :
>>> cannot fork Resource temporarily unavailable at ./test8.pl line 11.
>>> panic: MUTEX_LOCK (45) [op.c:354].

Suggestion install a handler for sigchld and reap them as they die
see below.
Warning dont do to much in the handler.
see man perlvar for %SIG

#!/usr/bin/perl

use warnings;
use strict;
my $pid;

sub foo{
    print ("process ",wait," died\n");
}

foreach my $incr (`seq 1 1 8`) {
    $SIG{CHLD}=\&foo;
    unless (defined ($pid = fork)) {
	die " cannot fork $!";
    }
    unless ($pid) {
	print " the sequence is $incr \n";
	exit;
    }
    print "pid is $pid\n";
}

###############

-- 
Bengt-Arne Fjellner




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