Why doesn't my Perl script use all CPU cores?

Question

Apparently, the script uses only one CPU core, and the machine has four. Is this my code or some other settings? I am new to Perl.

#!/usr/bin/perl

use strict;
use warnings;
use threads;
use threads::shared;
use Thread::Queue;
use DBI();
use File::Touch;

my $databasefile = "/var/www/deamon/new.db";
my $count        = touch($databasefile);

my $dbuser        = "****";
my $dbpwd         = "****";
my $dbhost        = "localhost";
my $dbname        = "****";
my $max_threads   = 16;
my $queue_id_list = Thread::Queue->new;
my @childs;

#feeds entries to the queue list
my $ArrayMonitor = threads->new(\&URLArrayMonitor, $queue_id_list);
sleep 3;    #make sure system has enough time to connect and load up array

#start 10 crawler threads (these are the work horses)
my $CrawlerThreads = ();
for (0 .. $max_threads) {
    $CrawlerThreads->[$_] = threads->new(\&NameChecker, $queue_id_list);

    #print "Crawler " . ($_ + 1) . " created.\n";
}

#print "Letting threads run until queue is empty.\n";

while ($queue_id_list->pending > 0) {
    sleep .01;
}

sleep 1;

foreach my $thr (threads->list) {

    # don't join the main or ourselves
    if ($thr->tid && !threads::equal($thr, threads->self)) {

        #print "Waiting for thread " . $thr->tid . " to join\n";
        #print "Thread " . $thr->join . " has joined.\n";
        sleep .01;
    }
}

sub URLArrayMonitor {
    my ($queue_id_list) = @_;

    #**********************************************
    # here we walk though all users / select database and check what needs to be checked
    #**********************************************
    my $dbh = DBI->connect("DBI:mysql:database=" . $dbname . ";host=" . $dbhost, $dbuser, $dbpwd, {'RaiseError' => 1});
    my $sth = $dbh->prepare("SELECT * FROM ci_users WHERE user_group >= 10 ORDER BY user_id");
    $sth->execute();
    while (my $ref = $sth->fetchrow_hashref()) {

        # now we check the user if there are names we need to check
        print "Now checking relian_user_" . $ref->{'user_id'} . "\r\n";
        eval {
            my $dbuser
              = DBI->connect("DBI:mysql:database=user_" . $ref->{'user_id'} . ";host=" . $dbhost, $dbuser, $dbpwd, {'RaiseError' => 1});
            my $stuser = $dbuser->prepare("SELECT * FROM ci_address_book WHERE lastchecked=0");    #select only new
            $stuser->execute();
            while (my $entry = $stuser->fetchrow_hashref()) {
                my @queueitem = ($ref->{'user_id'} . "#" . $entry->{'id'});
                $queue_id_list->enqueue(@queueitem);
            }
            $stuser->finish();
            $dbuser->disconnect();
        };
        warn "failed to connect - $dbuser->errstr" if ($@);
    }
    $sth->finish();
    $dbh->disconnect();
    print "List now contains " . $queue_id_list->pending . " records.\n";
    sleep 1;
}

sub NameChecker {
    my ($queue_id_list) = @_;
    while ($queue_id_list->pending > 0) {
        my $info = $queue_id_list->dequeue_nb;
        if (defined($info)) {
            my @details      = split(/#/, $info);
            my $result       = system("/var/www/deamon/NewScan/match_name db=" . $details[0] . " id=" . $details[1]);
            my $databasefile = "/var/www/deamon/new.db";
            my $count        = touch($databasefile);

            #print "Thread: ". threads->self->tid. " - Done user: ".$details[0]. " and addressbook id: ". $details[1]."\r\n";
            #print $queue_id_list->pending."\r\n";
        }
    }

    #print "Crawler " . threads->self->tid . " ready to exit.\n";

    return threads->self->tid;
}

Answer 1

, , , . ? &URLArrayMonitor , CPU, , Perl script. , &NameChecker, , ; CPU. , script .

, , :

use threads;
use Math::BigInt;
threads->new(sub {print new Math::BigInt($_[0])->bfac()}, 400000) for 1..10;
print `uptime` while sleep 5;