I confirm a serious problem. I get premature end of program. No exceptions (segfault), program just ends for no reason before its finished.

I has something to do with Scalar::Util::weaken

I've whittled the proof down to

#!/usr/bin/perl --
$Devel::Trace::TRACE = 0;   # Disable
use strict; use warnings; use XML::Twig;
Main( @ARGV );
warn "main who\n";
exit( 0 );
sub Main {
    my $self = {};
    $self->{xml} = XML::Twig::Elt->new('urlset', {
        'xmlns'        => 'http://www.google.com/schemas/sitemap/0.84'
+,
        'xmlns:xsi'    => 'http://www.w3.org/2001/XMLSchema-instance',
        'xsi:schemaLocation' => join(' ',
            'http://www.google.com/schemas/sitemap/0.84',
            'http://www.google.com/schemas/sitemap/0.84/sitemap.xsd',
        ),
    });

#~   <url>
#~     <loc>http://www.example.com/some/really/interesting/file.html</
+loc>
#~     <priority>0.5</priority>
#~   </url>

#~     for( 0 .. 149500 ){
#~     for( 0 .. 49500 ){
#~     for( 0 .. (49500-39500) ){
#~     for( 0 .. (10000 - 5000) ){
#~     for( 0 .. ( 5000 - 200 ) ){
#~     for( 0 .. ( 5000 - 140 ) ){
#~     for( 0 .. ( 5000 - 170 ) ){
#~     for( 0 .. ( 5000 - 180 ) ){
#~     for( 0 .. ( 5000 - 190 ) ){
#~     for( 0 .. ( 5000 - 183 ) ){
#~     for( 0 .. ( 5000 - 185 ) ){
#~     for( 0 .. ( 5000 - 183 ) ){
    for( 0 .. 4817 ){
        my @elements;
        push(@elements, XML::Twig::Elt->new('loc', {}, 'http://www.exa
+mple.com/some/really/interesting/file.html' ) );
        push(@elements, XML::Twig::Elt->new('priority', {}, '0.5' ) );
        my $elt = XML::Twig::Elt->new('url', {}, @elements);
        $elt->paste(last_child => $self->{xml});
        warn "main who $_\n" if $_ > ( 49497 - 3);
    }
    binmode STDOUT;
#~     print $self->{xml}->sprint();# FAIL,incomplete
    $self->{xml}->set_pretty_print('indented');
    my $header = '<?xml version="1.0" encoding="UTF-8"?>'."\n";
    
    $self->{xml}->print_to_file('2'); # NO cutoff XML s, but still exi
+ts on undef;
#~     $self->{xml}->purge; 
#~ Can't call method "purge_up_to" on an undefined value at C:/perl/si
+te/5.14.1/lib/XML/Twig.pm line 8087.

#~     print $header;
#~     $self->{xml}->print(); # XML is cut off
#~     print $self->{xml}->sprint(); # XML is cut off, no closing
#~     print $self->{xml}->flush; # fail
#~ Can't call method "flush_up_to" on an undefined value at C:/perl/si
+te/5.14.1/lib/XML/Twig.pm line 8082.

    warn "about to undef  ";
    $Devel::Trace::TRACE = 1;   # Enable
    undef $self->{xml};
    warn "after undef  ";
    return;
}

__END__
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The Devel::Trace shows sub XML::Twig::Elt::DESTROY checking whether to break circular reference manually, 4820 times (versus 4817 children), and skipping because we're using Scalar::Util::weaken

     undef $self->{xml};
>> C:/perl/site/5.14.1/lib/XML/Twig.pm:7534:     { my $elt= shift;
>> C:/perl/site/5.14.1/lib/XML/Twig.pm:7535:       return if( $XML::Tw
+ig::weakrefs);
>> C:/perl/site/5.14.1/lib/XML/Twig.pm:7534:     { my $elt= shift;
>> C:/perl/site/5.14.1/lib/XML/Twig.pm:7535:       return if( $XML::Tw
+ig::weakrefs);
...
[download]

Adding local $XML::Twig::weakrefs; before undef doesn't change the problem.

I'm using perl 5.14.1 on win32

$ perl -d:Modlist -e " use strict; use warnings; use XML::Twig; "
Carp                   1.23
Config
DynaLoader             1.13
Encode                 2.44
Encode::Alias          2.15
Encode::Config         2.05
Encode::Encoding       2.05
Exporter               5.65
Exporter::Heavy        5.65
File::Basename         2.82
File::Glob             1.12
File::Spec             3.33
File::Spec::Unix       3.33
File::Spec::Win32      3.33
List::Util             1.23
Scalar::Util           1.23
UNIVERSAL              1.08
XML::Parser            2.41
XML::Parser::Expat     2.41
XML::Twig              3.39
XSLoader               0.15
base                   2.16
bytes                  1.04
constant               1.21
feature                1.20
overload               1.13
utf8                   1.09
vars                   1.02
warnings               1.12
warnings::register     1.02
[download]