I believe I have determined the problem is that Text::CSV_XS is not thread-safe.

#!/usr/bin/perl
use threads;
use Thread::Queue;
#require Text::CSV_XS;

my $input = 'input.csv';
my $output = 'output.csv';
my @cols = qw(a b c d);
my $q;
my $count = 0;
while(1) {
        $q = Thread::Queue->new;
        my $inth = threads->create(\&inputthread);
        my $outth = threads->create(\&outputthread);
        $inth->join();
        $q->enqueue(undef);
        $outth->join() or die("thread crashed?\n");
        $count++;
        print "$count\n";
}

sub inputthread {
        require Text::CSV_XS;
        $csv = Text::CSV_XS->new ({ binary => 1, eol => "\n", sep_char
+ => ",", quote_char => '"', escape_char => '"', empty_is_undef => 0, 
+decode_utf8 => 0 });
        $csv->column_names(@cols);
        my $fh;
        open($fh,'<',$input);
        binmode($fh);
        my @rows = ();
        while(1) {
                my $data;
                if($csv) {
                        $data = $csv->getline_hr($fh);
                        unless($data) {
                                last if($csv->eof);
                                die("Failed to parse CSV line: ".$csv-
+>error_diag."\n");
                        }
                }
                else {
                        die("Data parsed another way\n");
                }
                my @arr = values(%$data);
                push(@rows,\@arr);
        }
        close($fh);
        $q->enqueue(\@rows);
}

sub outputthread {
        my $fh;
        open($fh,'>',$output);
        binmode($fh);
        my $csv;
        require Text::CSV_XS;
        $csv = Text::CSV_XS->new ({ binary => 1, eol => "\n", sep_char
+ => ',', quote_char => '"', escape_char => '"' });
        while(1) {
                my $rows = $q->dequeue;
                last unless(defined $rows);
                foreach my $data(@$rows) {
                        if($csv) {
                                $csv->print($fh,$data);
                        }
                        else {
                                die("Data output another way\n");
                        }
                }
        }
        close($fh);
        return 1;
}
[download]

If I require the Text::CSV_XS module before starting the threads, it seems to resolve the problem. Can anyone confirm that, because I would hate to have more intermittent issues come up.

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