sub do_worker {
        my $t = threads->self()->tid();
        {
            lock %{ $stat{'work'} };
            $stat{'work'}{ $t } = &share( {} );
            $stat{'work'}{ $t }{'stat'} = 'idle';
        }
        my $c;
LOOP:    while ( do{ lock %{ $stat{'work'}{$t} }; $stat{'work'}{$t}{'stat'} } ne 'done' ) {
...
    if ( my $thread = threads->new( \&do_worker ) ) {
        my $t = $thread->tid;
        trc 'dbg',  'new worker created';
        $thread->detach;
...