Why am I getting a segmentation fault when I use binmode with threads in Perl?

Question

Hi Folks,

this call

my $th = threads->create(\&print, "Hello thread World!\n");
$th->join();

works fine. But as soon as I add

binmode(STDOUT, ":encoding(ISO-8859-1)");

to my script file, I get an error like "segmentation fault", "access denied".

What is wrong to define an encoding type when trying to call a perl thread?

Example:

use strict; use warnings;
use threads;

binmode(STDOUT, ":encoding(ISO-8859-1)");

my $th = threads->create(\&print, "Hello thread World!\n");
$th->join();

sub print {
    print @_;
}

This code does not work for me.

Kind Regards

--Andy

Answer 1

First, note that having a subroutine print with the same name as a built-in function is likely to cause a lot of confusion (if not to perl definitely to you or anyone who needs to read your code).

Second, I do not observe the problem with:

#!/usr/bin/perl

use strict; use warnings;
use threads;

my $th = threads->create(\&print, "Hello thread World!\n");
$th->join();

sub print {
    binmode(STDOUT, ":encoding(ISO-8859-1)");
    print @_;
}

Output:

C:\Temp> t
Hello thread World!

However, since STDOUT is a package variable, I would not recommend doing anything like this.

You should post a short but complete script that exhibits the problem rather than bits and pieces and also describe what you are trying to do rather than just the mechanical steps.

Answer 2

This was reported as bug in Perl's bug tracker. I have same failure on 5.12 RC0 on Windows.