I have this script that is using threads, queues and a shared variable. once the queue is empty, i have a few threads that hang, and hence the program never finishes.

the script is actually quite simple, reading from a file (which happens to be IP addresses) queuing said data, then in each thread, dequeuing an ip address and doing an snmpget on it.

i can help but think i'm missing something fundamental here.

#!/usr/bin/perl -w

use strict;

use threads;
use threads::shared;
use Thread::Queue;

my $q = new Thread::Queue;      # create empty threaded queue
my $threadcount = 10;           # amount of threads
my @SNMPthreads;                # thread tracker

my @firmware : shared;

open (FH, 'filename.txt');

while (<FH>) {
    chomp;
    $q->enqueue($_);
}
close FH;

foreach my $i (1..$threadcount) {
    push @SNMPthreads, threads->new(\&SNMPthread, $i );
}

foreach my $i (0..$#SNMPthreads) {
    my $retval = $SNMPthreads[$i]->join();
}

open (WH, ">firmware.txt");
print WH "-->$_\n" foreach @firmware;
close WH;

sub SNMPthread  {
    my $thread = shift;
    while ( $q->pending && $q->pending > 0) {
        my $left = $q->pending;
        my $ip = $q->dequeue;
        push @firmware, "$$: $thread, $left, $ip";
        my $retval = `/usr/bin/snmpget -v1 -c <commstring> $ip sysDesc
+r.0`;
        chomp $retval;
        $retval =~ s/\>\>//g;
        my @ele = split(/\;/, $retval);
        print "$ip, $ele[ ($#ele-1) ], $ele[ $#ele ]\n";
    }
    print "thread $thread finished\n";

}
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Summary of my perl5 (revision 5 version 8 subversion 7) configuration:
  Platform:
    osname=linux, osvers=2.6.14.3, archname=i486-linux-gnu-thread-mult
+i
    uname='linux ninsei 2.6.14.3 #1 smp preempt mon nov 28 19:51:50 ps
+t 2005 i686 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dccc
+dlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr -Dprivlib=/usr/
+share/perl/5.8 -Darchlib=/usr/lib/perl/5.8 -Dvendorprefix=/usr -Dvend
+orlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/
+local -Dsitelib=/usr/local/share/perl/5.8.7 -Dsitearch=/usr/local/lib
+/perl/5.8.7 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/ma
+n3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man
+3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -
+Ud_csh -Uusesfio -Uusenm -Duseshrplib -Dlibperl=libperl.so.5.8.7 -Dd_
+dosuid -des'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=undef useithreads=define usemulti
+plicity=define
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS 
+-DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE
+_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN 
+-fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.0.3 20051201 (prerelease) (Debian 4.0.
+2-5)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=1
+2
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
+ lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=/lib/libc-2.3.5.so, so=so, useshrplib=true, libperl=libperl.s
+o.5.8.7
    gnulibc_version='2.3.5'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'


Characteristics of this binary (from libperl):
  Compile-time options: MULTIPLICITY USE_ITHREADS USE_LARGE_FILES
                        PERL_IMPLICIT_CONTEXT
  Locally applied patches:
        SPRINTF0 - fixes for sprintf formatting issues - CVE-2005-3962
  Built under linux
  Compiled at Dec 15 2005 17:19:17
  @INC:
    /etc/perl
    /usr/local/lib/perl/5.8.7
    /usr/local/share/perl/5.8.7
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.8
    /usr/share/perl/5.8
    /usr/local/lib/site_perl
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is anyone able to offer advice on this hangage ?