From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Pravin
Talegaonkar
Sent: 19 January 2006 11:36
To: [email protected]
Subject: Threads in Perl
> Dear Gurus,
>
> I need to use threads in Perl. I have following requirement. I need to
process few files at a given time, I
> used to use following approach
>
> 1) Get the names of all the files in Array
> 2) Process all the files one by one.
>
> This was a simple one, but it takes lot of time and hence I decided to
use threads. What I wanted was
> 1) Get the names of all the files in Array
> 2) Process 2 files at a given time.
> 3) In case any of the file finishes processing, immediately process
next file from the array. So that at any
> given instance, script should process 2 files (Of course excluding the
last instance).
I would suggest using a queue (Thread::Queue) rather than an array. For
example:
use strict;
use warnings;
use threads;
use Thread::Queue;
my @files = ('A'..'Z');
my $nthreads = shift || 3;
die "Thread count should be between 1 and 10\n"
unless $nthreads > 1 && $nthreads < 11;
my $file_queue = Thread::Queue->new;
# Populate the queue before starting the threads, because they will
# exit if the queue is empty.
$file_queue->enqueue(@files);
# Start threads
my @thread_list;
for (1..$nthreads) {
my $thr = threads->create(\&thread_sub, $file_queue)
or die "Failed to create thread: $!\n";
push @thread_list, $thr;
}
# Wait for threads to finish
foreach my $thr (@thread_list) {
$thr->join();
}
# Thread function. Process files until none left then exit.
sub thread_sub {
my $file_queue = shift;
my $thr = threads->tid();
while (my $filename = $file_queue->dequeue_nb()) {
print "Thread $thr processing file $filename\n";
sleep 1;
}
}
HTH
--
Brian Raven
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