Re^4: Parallel::ForkManager (high cpu and a lot of memory)

[marto9]

Thx for all the help so far!

But I still have a question in my mind.
If I would code thesame in c++ for example. Would the process use less memory and cpu?

[BrowserUk]

It depends. If you used MFC or STL probably not. If you use ATL maybe. If you eshew the use of template libraries altogether and write directly to the API (Win32 or POSIX) probably.

But the other side of that equation is instead of 15 or 20 lines of code you'll end up writing 100s. And they will be much harder to get right, and much, much harder to debug when they go wrong.

You could also substantially reduce the memory consumption of the Perl program by avoiding LWP and writing your own socket code. For what you are doing it wouldn't be very complex, but it would be much harder to get right.

Or you can strike a compromise and use LWP::Simple and a pool of threads. This version uses ~20MB and < 3% cpu for 10 threads on my system:

#! perl -slw
use strict;
use threads;
use LWP::Simple;
use threads::shared;
use Thread::Queue;

$|++;
our $THREADS ||= 10;

my $sem :shared;
my $Q = new Thread::Queue;

sub worker {
    while( my $url = $Q->dequeue ) {
        chomp( $url );
        { lock $sem; print "fetching $url" }
        my $content = get "http://$url/";
        lock $sem; 
        print "$url : ", $content && $content =~ /ok/ ? 'ack' : 'nack'
+ 
    }
}

$Q->enqueue( <> );
$Q->enqueue( (undef) x $THREADS );

my @threads = map threads->create( \&worker ), 1 .. $THREADS;

$_->join for @threads
__END__

C:\test>715836 urls.txt
fetching www.bbc.co.uk
fetching news.bbc.co.uk
fetching www.ibm.com
fetching www.yahoo.com
fetching www.microsoft.com
fetching www.google.com
fetching www.google.co.uk
fetching www.google.co.au
fetching www.cnn.com
fetching www.msnbc.com
www.google.co.au : nack
fetching www.perl.org
www.google.co.uk : ack
fetching www.nasa.com
www.yahoo.com : nack
fetching www.ask.com
www.google.com : ack
fetching www.itv.com
www.perl.org : nack
www.nasa.com : nack
www.ask.com : nack
www.msnbc.com : ack
www.itv.com : nack
www.ibm.com : ack
www.microsoft.com : ack
news.bbc.co.uk : ack
www.cnn.com : ack
www.bbc.co.uk : ack