sub syncIdle {
	# Check if any thread errored out
	my $abort = 0;
	for my $i (0..$#thread) {
		if	(	!$thread[$i]->is_running()
			||	$thread[$i]->is_joinable()
			) {
			lock($screenaccess);
			print	(STDERR
					  'ERROR: thread #'
					, 1+$i
					, ' encountered a problem while processing file'
					, "\n"
					, $log[1+$i]
					, "\n"
					, 'Check the cause and eventually report a bug.'
					, "\n"
					);
			$abort ||= 1;
		}
	}
	if ($abort) {
		endThreadedOperation();
		print (STDERR "${VTred}Flushing and aborting now ...${VTnorm}\n");
		print (STDERR 'The error message may have scrolled out due to asynchronous operation. Check.', "\n");
		exit(1);
	}

	while ($busy || 0 < $dispatcher->pending()) {
		threads->yield();
# 		sleep(1);	# Retry later
	}
}