Fun with Threads - "Attempt to free unreferenced scalar during globaldestruction."

[Stuart Moore]

My aim is to have a module, "ToolsThread", which I can pass commands to so
that it'll execute them in its own thread. However when I call join on the
thread, it seems to all go wrong. It all behaves as normal up to the point
I call join on the thread in the quit function, then it gives me the
message

Attempt to free unreferenced scalar during global destruction.

I'm not sure what that means, but I don't like it.

Here is the relevant code (ToolsThread.pm is the module, testToolsThread
is a basic test script. I would have more code in the loop eventually,
assuming I can get it to work)

##ToolsThread.pm
package ToolsThread;

use strict;
use warnings;
use threads;
use threads::shared;
use Thread::Queue;

our $queue = new Thread::Queue;
our $thread = threads->create(\&Run,$queue);

sub Run{
my $queue = shift;
while(1){
my $incoming = $queue->dequeue;
if ($incoming eq "quit"){
last;
}
}
}

sub Quit{
$queue->enqueue('quit');
$thread->join();
}

##testToolsThread.pl
use strict;
use warnings;
use threads;
use threads::shared;
use Thread::Queue;
use ToolsThread;

ToolsThread::Quit;

[Bryan Castillo]

Stuart Moore <stjm2@hermes.cam.ac.uk> wrote in message news:<Pine.SOL.4.44.0306271347280.25299-100000@orange.csi.cam.ac.uk>...

> My aim is to have a module, "ToolsThread", which I can pass commands to so
> that it'll execute them in its own thread. However when I call join on the
> thread, it seems to all go wrong. It all behaves as normal up to the point
> I call join on the thread in the quit function, then it gives me the
> message
>
> Attempt to free unreferenced scalar during global destruction.
>
> I'm not sure what that means, but I don't like it.
>
> Here is the relevant code (ToolsThread.pm is the module, testToolsThread
> is a basic test script. I would have more code in the loop eventually,
> assuming I can get it to work)
>
> ##ToolsThread.pm
> package ToolsThread;
>
> use strict;
> use warnings;
> use threads;
> use threads::shared;
> use Thread::Queue;
>
> our $queue = new Thread::Queue;
> our $thread = threads->create(\&Run,$queue);

# change to this (I don't know why it is like this though)
our $thread = threads->create("Run",$queue);

>
> sub Run{
> my $queue = shift;
> while(1){
> my $incoming = $queue->dequeue;
> if ($incoming eq "quit"){
> last;
> }
> }
> }
>
> sub Quit{
> $queue->enqueue('quit');
> $thread->join();
> }
>
> ##testToolsThread.pl
> use strict;
> use warnings;
> use threads;
> use threads::shared;
> use Thread::Queue;
> use ToolsThread;
>
> ToolsThread::Quit;