jackyex has asked for the wisdom of the Perl Monks concerning the following question: 

Hello...
I want to make a perl script that will use ForkManager and have some v
+ariables loop inside like this :

1. I have file x:
jacky@ubuntu:~/Desktop$ cat x
1
2
3
4
5
########################
2. And I have file y:
jacky@ubuntu:~/Desktop$ cat y
jack
john
joe
########################
3. I than have script.pl:
jacky@ubuntu:~/Desktop$ cat script.pl:

#!/usr/bin/perl

use Parallel::ForkManager;
use LWP::Simple;

my $file = x;
my $pm = new Parallel::ForkManager(3);
open($fileh, "<" . $file);
while (<$fileh>) {
$pm->start and next;
        $linex = $_;
        $linex =~ s/\x0a//g;
        open OUTPUT,">$linex";
        print OUTPUT ("$linex\n");
        close OUTPUT;
        $pm->finish   
   }
        close($fileh);
$pm->wait_all_children();

##################################
Now I want inside the line "print OUTPUT ("$linex\n");" to do somethin
+g like this "print OUTPUT ("$linex$liney\n");" and loop the content o
+f "y" file inside every "$linex" file created...in the end I want the
+ $linex files with this content:
cat 1 = 1jack
cat 2 = 2john
cat 3 = 3joe
cat 4 = 1jack
cat 5 = 2john

Is that possible? Thank you and please excuse my bad english, Jack

[download]

Replies are listed 'Best First'.
Re: Variables loop in Parallel::ForkManager
by ikegami (Patriarch) on Nov 29, 2008 at 21:43 UTC

    Without forking, it would be 

    open(my $fh_x, '<', 'x') or die $!;
while (<$fh_x>) {
    chomp( my $linex = $_ );
    open my $fh_y,   '<', 'y'    or die $!;
    open my $fh_out, '>', $linex or die $!;
    while (<$fh_y>) {
       chomp( my $liney = $_ );
       print $fh_out ("$linex$liney\n");
    }
}

    [download]

    So with forking, it would be 

    open(my $fh_x, '<', 'x') or die $!;
while (<$fh_x>) {
    $pm->start and next;
    chomp( my $linex = $_ );
    open my $fh_y,   '<', 'y'    or die $!;
    open my $fh_out, '>', $linex or die $!;
    while (<$fh_y>) {
       chomp( my $liney = $_ );
       print $fh_out ("$linex$liney\n");
    }
    $pm->finish   
}

    [download]

    Since every thread reads file y, you could preload it into memory to save the threads from all doing the same work.

    Without forking, it would be 

    my @y;
{
   open my $fh_y, '<', 'y' or die $!;
   chomp( @y = <$fh_y> );
}


open(my $fh_x, '<', 'x') or die $!;
while (<$fh_x>) {
    chomp( my $linex = $_ );
    open my $fh_out, '>', $linex or die $!;
    for my $liney (@y) {
       print $fh_out ("$linex$liney\n");
    }
}

    [download]

    So with forking, it would be 

    my @y;
{
   open my $fh_y, '<', 'y' or die $!;
   chomp( @y = <$fh_y> );
}


open(my $fh_x, '<', 'x') or die $!;
while (<$fh_x>) {
    $pm->start and next;
    chomp( my $linex = $_ );
    open my $fh_out, '>', $linex or die $!;
    for my $liney (@y) {
       print $fh_out ("$linex$liney\n");
    }
    $pm->finish   
}

    [download]

    Update: Added preloading version.
    Update: Fixed bug mentioned in reply.

[reply]
[d/l]
[select]
      Thank you but it doesn't work...Maybe I'm doing something wrong :

#!/usr/bin/perl
use Parallel::ForkManager;

my $pm = new Parallel::ForkManager(3);

my @y;
{
   open my $fh_y, '<', 'y' or die $!;
   chomp( @y = <$fh_y> );
}

open(my $fh_x, '<', 'x') or die $!;
while (<$fh_x>) {
    $pm->start and next;
    chomp( my $linex = $_ );
    open my $fh_out, '>', $linex or die $!;
    for (@y) {
       print $fh_out ("$linex$liney\n");
    }
    $pm->finish   
}

When I perl script.pl it gives me the 5 "$filex" files but like this :

jacky@ubuntu:~/Desktop/test$ cat 1
1
1
1

So definatelly there is something wrong in there...Thank you again

      [download]
[reply]
[d/l]
        for (@y) should be for my $liney (@y)
[reply]
[d/l]
[select]

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