The Thread::Queue::Any documentation describes the usage of each object method but doesn't give an example using threads.

The following code was my first attempt to get Thread::Queue::Any working with threads:

#!/opt/perl-5.8.2/bin/perl -w

use strict;
use threads;
use Thread::Queue::Any;

my $queue = Thread::Queue::Any->new;

my $prod_thread = new threads(\&producer);
my $cons_thread = new threads(\&consumer);

$prod_thread->join;
$cons_thread->join;

sub producer {
        my $value = 1234;
        $queue->enqueue( $value );
        $queue->enqueue( undef );
}

sub consumer {
        while( my($returned_value) = $queue->dequeue ) {
                printf "I have been returned: %i\n", $returned_value;
        }
}
[download]

but running it produces:

I have been returned: 1234
Use of uninitialized value in printf at ./2.pl line 23.
I have been returned: 0
[download]

and then it just sits there doing nothing.

The Perl 5.8.0 thread tutorial uses the idiom of enqueuing an undef to a queue so that the while loop handling dequeuing exits when the undef is dequeued. This does not seem to work with Thread::Queue::Any. Should it?

In an example given in the above tutorial, the queue is passed to the thread as a parameter for the sub. I thought I might need something like that with Thread::Queue::Any so I tried the next piece of code:

#!/opt/perl-5.8.2/bin/perl -w

use strict;
use threads;
use Thread::Queue::Any;

my $queue = Thread::Queue::Any->new;

my $prod_thread = new threads(\&producer, $queue);
my $cons_thread = new threads(\&consumer, $queue);

$prod_thread->join;
$cons_thread->join;

sub producer {
        my $queue = $_[0];
        my $value = 1234;
        $queue->enqueue( $value );
        $queue->enqueue( undef );
}

sub consumer {
        my $queue = $_[0];
        while( my($returned_value) = $queue->dequeue ) {
                printf "I have been returned: %i\n", $returned_value;
        }
}
[download]

but this too produced:

I have been returned: 1234
Use of uninitialized value in printf at ./3.pl line 25.
I have been returned: 0
[download]

and then just sat there too.

And so we reach my question - how should I really be using Thread::Queue::Any across threads?

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