The inevitable simple, threaded solution: 

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

my $Q = new Thread::Queue;
my $cmd =
'perl -le"$|++;print $$ . q[:] . localtime()  and sleep 1 for 1..rand(
+10)" |';

async{
    my $pid1 = open my $fh, $cmd or die $!;
    $Q->enqueue( $_ ) while <$fh>;
    close $fh;
    $Q->enqueue( undef );
}->detach;

async{
    my $pid2 = open my $fh, $cmd or die $!;
    $Q->enqueue( $_ ) while <$fh>;
    close $fh;
    $Q->enqueue( undef );
}->detach;

for( 1.. 2 ) {
    while( defined( local $_= $Q->dequeue ) ) {
        chomp;
        print;
    }
}

__END__
c:\test>junk6
3140:Wed Oct  1 16:04:35 2008
216:Wed Oct  1 16:04:35 2008
3140:Wed Oct  1 16:04:36 2008
216:Wed Oct  1 16:04:36 2008
3140:Wed Oct  1 16:04:37 2008
216:Wed Oct  1 16:04:37 2008
3140:Wed Oct  1 16:04:38 2008
216:Wed Oct  1 16:04:38 2008
216:Wed Oct  1 16:04:39 2008
216:Wed Oct  1 16:04:40 2008
216:Wed Oct  1 16:04:41 2008

c:\test>junk6
3308:Wed Oct  1 16:04:46 2008
3804:Wed Oct  1 16:04:46 2008
3308:Wed Oct  1 16:04:47 2008
3308:Wed Oct  1 16:04:48 2008
3308:Wed Oct  1 16:04:49 2008
3308:Wed Oct  1 16:04:50 2008
3308:Wed Oct  1 16:04:51 2008
3308:Wed Oct  1 16:04:52 2008

[download]
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

In reply to Re: working with 2 inputs by BrowserUk
in thread working with 2 inputs by sktron

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