my @threads = map threads->new( \&processrefsthread, $Q ), 1 .. $T;

##</code><code>##

sub threadProc {
    my $code = shift;
    for(1 .. 5 ){
        my @rv = eval { $code->( @_ );  };
        if( $@ ) {
            ## log errors if applicable
            ## next if retrying makes sense.
            ## last if not.
            tprint "$@; retrying";
        }
        else {
            return @rv; ## return any return values if applicable.
            ## think about scalar/list/void context.
        }
    }
}

my @threads = map threads->new( \&threadProc, \&processrefsthread, $Q ), 1 .. $T;

##</code><code>##

sub processrefsthread {
    my $Q = shift;
    tprint 'Starting';
    while( my $job = $Q->dq() ) {
        tprint "processing job $job";

        my $d = int(rand(5));
        unless( $d ) {
            12345 / $d;
        }
        for my $i (0 .. $d * 500000) {
            my $j = $i * $d;
            $j = int(rand($j));
        }
    }
    tprint 'Ending';
}

##</code><code>##

C:\test>1056140-buk
Useless use of division (/) in void context at C:\test\1056140-buk.p
[1] Starting
[2] Starting
[3] Starting
[4] Starting
[2] processing job 1
[1] processing job 2
[3] processing job 3
[4] processing job 4
[4] processing job 5
[4] processing job 6
[1] processing job 7
[3] processing job 8
[4] processing job 9
[4] Illegal division by zero at C:\test\1056140-buk.pl line 25.
; retrying
[4] Starting
[2] processing job 10
[4] processing job 11
[2] Illegal division by zero at C:\test\1056140-buk.pl line 25.
; retrying
[2] Starting
[2] processing job 12
[3] processing job 13
[2] processing job 14
[1] processing job 15
[1] Illegal division by zero at C:\test\1056140-buk.pl line 25.
; retrying
[1] Starting
...

##</code><code>##

my $Q - ...;

sub thread {
    while( $Q->dq( ) )
        ...
    }
}