Here is my latest 2 implementations. They both allow me to detach the thread without a hang. Only the first one gets back the information even in the case of it waiting for user input. But I am not sure if either is exactly thread safe, and I am not sure I am using the thread queue as you intended. But this was the way I could get it working.

Implementation 1:

my $queue = new Thread::Queue;
my $command = 'diskpart';
my $status = _timedCommand($command, 90);
if ($status eq 'TIMEOUT') {
    print "\n=======TIMEOUT==========\n";
}
my @ans;
while (my $ref = $queue->dequeue_nb()) {
    if (ref($ref) =~ m/ARRAY/i) {
        push(@ans, @$ref);
    }
    else {
        push(@ans, $ref);
    }
}
print "@ans\n";

sub _timedCommand
{
    my ($command, $time) = @_;
    my $pid :shared;
    my @tmp :shared;

    my $thr = async {
        $pid = open my $fh, "$command |" or die "$!";
        push @tmp, $_ while <$fh>;
        $fh->close();
    };

    while ($thr->is_running() and $time > 0) {
        sleep(1);
        $time--;
    }
    if ($thr->is_joinable()) {
        $thr->detach();
        $queue->enqueue(\@tmp);
        return 'OK';
    }
    else {
        $thr->detach;
        kill 3, $pid;
        $queue->enqueue(\@tmp);
        return 'TIMEOUT';
    }
}
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Implementation 2:

my $queue = new Thread::Queue;
my $command = 'diskpart';

my $status = _timedCommand($command, 90);
if ($status eq 'TIMEOUT') {
    print "\n=======TIMEOUT==========\n";
}
my @ans;
while (my $ref = $queue->dequeue_nb()) {
    if (ref($ref) =~ m/ARRAY/i) {
        push(@ans, @$ref);
    }
    else {
        push(@ans, $ref);
    }
}

print "@ans\n";

sub _timedCommand
{
    my ($command, $time) = @_;
    my $pid :shared;

    my $thr = async {
        $pid = open my $fh, "$command |" or die "$!";
        my @tmp :shared;
        push @tmp, $_ while <$fh>;
        $queue->enqueue(\@tmp);
        $fh->close();
    };

    while ($thr->is_running() and $time > 0) {
        sleep(1);
        $time--;
    }
    if ($thr->is_joinable()) {
        $thr->detach();
        return 'OK';
    }
    else {
        $thr->detach;
        kill 3, $pid;
        return 'TIMEOUT';
    }
}
[download]

In the second implementation I am seeing some wonky stuff when running the diskpart command, at times it @ans is populated and it prints out information, at other times it is not and doesn't. I have to assume its a timing issue, but I am not sure where it would be. For a dir command it works as expected.

Output from Implementation 1:

C:\Sandbox>perl ForkProcessTimeout.pl

=======TIMEOUT==========

 Microsoft DiskPart version 5.1.3565

 Copyright (C) 1999-2003 Microsoft Corporation.
 On computer: USITPAPADGD1C

 DISKPART>
[download]

Output from Implementation 2:

The output is inconsistent:

C:\Sandbox>perl ForkProcessTimeout.pl

=======TIMEOUT==========

 Microsoft DiskPart version 5.1.3565

 Copyright (C) 1999-2003 Microsoft Corporation.
 On computer: USITPAPADGD1C

 DISKPART>

C:\Sandbox>perl ForkProcessTimeout.pl

=======TIMEOUT==========

C:\Sandbox>perl ForkProcessTimeout.pl

=======TIMEOUT==========

 Microsoft DiskPart version 5.1.3565

 Copyright (C) 1999-2003 Microsoft Corporation.
 On computer: USITPAPADGD1C

 DISKPART>
[download]

I think implementation 2 is the way I need to go for it to be threadsafe, but I don't get the consistency in output. Also when I run implementation 2 in the debugger it seems to consistently include the output.