my %jobNos :shared;
...
sub job {
    my $tid = threads->tid;
    my $jobNo;

    sleep 1 until do{ lock %jobNos; $jobNo = $jobNos{ $tid } };
    
    ## now use $jobNo.
    ...
}

my $thread = threads->create( \&job );

... some time later

{ lock %jobNos; $jobNos{ $thread->tid } = getJobNo() };
...