--- kikuchiyo1.pl	2023-01-27 23:31:34.592261566 -0600
+++ kikuchiyo2.pl	2023-01-27 23:31:12.488762580 -0600
@@ -92,12 +92,16 @@
 for my $worker_id (0..$maxforks-1) {
 	if (my $pid = fork) {
 		++$forkcount;
+	} elsif (!defined $pid) {
+		warn "fork failed for worker_id $worker_id\n";
 	} else {
 		for my $i (0..$#{$batched_data[$worker_id]}) {
 			my $infile = $batched_data[$worker_id][$i];
 			my $subdir = $worker_id + 1;
-			open my $IN, '<', $infile or exit(0);
-			open my $OUT, '>', "$tempdir/$subdir/text-$i" or exit(0);
+			open my $IN, '<', $infile
+				or die "[$worker_id] open error: infile";
+			open my $OUT, '>', "$tempdir/$subdir/text-$i"
+				or die "[$worker_id] open error: outfile\n";
 			while (<$IN>) {
 				tr/-!"#%&()*',.\/:;?@\[\\\]”_“{’}><^)(|/ /; # no punct "
 				s/^/ /;