If you are on a *NIX box, type cat /proc/cpuinfo to see how many processors you have on the machine this code runs on. Remember, multi-threading works better on a multi-processor box.

Having said that, why aren't you being more general? You have a subroutine for each thread that does the same thing: 

sub australianNationalUniversity {
    use AustralianNationalUniversity;
    AustralianNationalUniversity::search( $maxHits, %searchTerms );
    my @results = AustralianNationalUniversity::getResults();
    lock(@searchResults);
    push ( @searchResults, @results );
}

[download]
You should generalize that. Something like this untested piece of code: 
# at the beginning of your code:
use GenericSearch;

# and then just ONE sub for all threads
sub get_search {
    my $group = shift;
    GenericSearch::search($group, $maxHits, %searchTerms );
    my @results = GenericSearch::getResults();
    lock(@searchResults);
    push ( @searchResults, @results );
}

[download]
Also, why hold each thread in a seperate variable? Why not store them in an array instead? Because you have 13 seperate search items? Nonesense! Just "tag" them with a leading underscore (or whatever) so you can grep them out of CGI::param() like so: 
my @search = grep /^_/, param();

# now remove the underscores
$_ = substr($_,1) for @search;

# now create the threads;
my @thread = map { threads->new(sub {get_search($_)})}, @search;

# and finally, join them when done
$_->join for @thread;

[download]
Code smart, not hard. ;)

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

In reply to Re: Question about threads by jeffa
in thread Question about threads by Gwalchmai

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