PDF::API2, $pdf->end

Tharg has asked for the wisdom of the Perl Monks concerning the following question:

Hi - I have a problem where sometimes this method will cause the script to fail with the error "Can't upgrade that kind of scalar at /usr/lib/perl5/site_perl/5.8.8/PDF/API2/Basic/PDF/Objind.pm line 150", This will always happen with the same source PDF in the same job. Basically I'm doing :

use strict;
use PDF::API2;

my $source_pdf = $ARGV[0];
my $dest_pdf = $ARGV[1];

my $pdf_d = PDF::API2->new();
my $pdf_s = PDF::API2->open($source_pdf);

for ( my $pdf_page = 1 ;  $pdf_page <= $pdf_s->pages ; $pdf_page++ ){
  my $pdf_d_page = $pdf_d->page();
  my $pdf_d_pageform = $pdf_d->importPageIntoForm($pdf_s, $pdf_page);
  my $pdf_d_gfx = $pdf_d_page->gfx;

  $pdf_d_gfx->formimage($pdf_d_pageform, 0, 0, 1);
}

$pdf_s->end();
$pdf_d->saveas($dest_pdf);
$pdf_d->end();
[download]

except that there is a lot of other code and all of the above is in several other loops etc. There're a lot of source pdfs. The "$pdf_s->end();" will cause the error in the bad cases.

I'm afraid that I'm unable to supply the actual code or the source, problem pdfs.

While I can duplicate this 100% when it happens (perhaps with 1 in 100,000 source pdfs) with the actual script and I have isolated that the "$pdf_s->end()" is the problem line, I have not been able to replicate it in smaller test scripts using the same source pdfs yet. However I have found that if I replace the $pdf_s->end() with undef($pdf_s) everything seems to go perfectly in the production script with the problem source pdfs.

So I ask for your wisdom, Monks. Is replacing $pdf_s->end() as described a bad idea for some reason that I'm unaware of? Thanks.

Comment on PDF::API2, $pdf->end Download Code

Replies are listed 'Best First'.
Re: PDF::API2, $pdf->end by johnny_carlos (Scribe) on Nov 04, 2011 at 20:09 UTC
I may not be wise enough for commenting here, but no one else has so I guess it's better than nothing :) The code snippet looks good(to me), but you indicate that the real code is in "several other loops". Is it possible you are calling $pdf_s->end on a file that already had $pdf_s->end called on it? Is it possible that a particular pdf is causing the problem, have you kept track of the file names, and output the name of the current file when it crashes?	[reply]
Re^2: PDF::API2, $pdf->end by Tharg (Scribe) on Nov 07, 2011 at 09:55 UTC
Re "Is it possible you are calling $pdf_s->end on a file that already had $pdf_s->end called on it? ", no, afraid not. Re "Is it possible that a particular pdf is causing the problem, have you kept track of the file names, and output the name of the current file when it crashes? " yes, absolutely. After the fact I know what file has caused the problem and if I use the same script etc again on it (on it's own or with other source files) I get the same results. However I haven't found anything common with the problem source pdfs yet.	[reply]
Re: PDF::API2, $pdf->end by pvaldes (Chaplain) on Nov 04, 2011 at 20:09 UTC
what is in the line 150?	[reply]
Re^2: PDF::API2, $pdf->end by Tharg (Scribe) on Nov 07, 2011 at 10:02 UTC
Here's the whole function that contains that line, with line 150 commented like "# LINE 150": sub release { my ($self, $force) = @_; my (@tofree); return($self) unless(ref $self); # delete stuff that we know we can, here if ($force) { foreach my $key (keys %{$self}) { push(@tofree,$self->{$key}); $self->{$key}=undef; delete($self->{$key}); } } else { @tofree = map { delete $self->{$_} } keys %{$self}; } while (my $item = shift @tofree) { my $ref = ref($item); if (UNIVERSAL::can($item, 'release')) # LINE 150 { $item->release($force); } elsif ($ref eq 'ARRAY') { push( @tofree, @{$item} ); } elsif (UNIVERSAL::isa($ref, 'HASH')) { release($item, $force); } } # check that everything has gone - it better had! foreach my $key (keys %{$self}) { # warn ref($self) . " still has '$key' key left after release. +\n"; $self->{$key}=undef; delete($self->{$key}); } } [download]	[reply] [d/l]