Good evening!

I am attempting to merge several thousand small (<20KiB) PDF file together into one PDF using PDF::API2.

The merging script works correctly at the beginning, but quickly bogs down after processing ~100 PDFs before grinding to a halt with the following warnings: 

Deep recursion on subroutine "PDF::API2::Basic::PDF::Objind::release" 
+at C:/Perl64/site/lib/PDF/API2/Basic/PDF/Objind.pm line 123.
Deep recursion on subroutine "PDF::API2::Basic::PDF::Objind::release" 
+at C:/Perl64/site/lib/PDF/API2/Basic/PDF/Objind.pm line 123.
Deep recursion on subroutine "PDF::API2::Basic::PDF::Objind::release" 
+at C:/Perl64/site/lib/PDF/API2/Basic/PDF/Objind.pm line 123.
...

[download]

Here is a small sample merging script that exhibits the problem
(the script used to generate the sample PDF files can be found in the READMORE section): 

#!/usr/bin/perl
use 5.018;
use PDF::API2;
use strict;
use warnings;

my $path = "./pdfs/";
my $out_pdf_file = 'merged.pdf';
my $out_pdf;

opendir (my $DIR, $path) or die "Could not open $path:\n$!\n$^E";
chdir $path;

while ( my $in_pdf_file = readdir $DIR ) {
  next if $in_pdf_file =~ /^\./;
  
  my $in_pdf = PDF::API2->open($in_pdf_file) or die "Error opening PDF
+ file [$in_pdf_file]:\n$!\n$^E";
  
  # Append to output if PDF already exists
  if ( -e $out_pdf_file ) {
    $out_pdf = PDF::API2->open($out_pdf_file);
  }
  
  # Create new PDF if output does not exist
  else {
    $out_pdf = PDF::API2->new(-file => $out_pdf_file);
  }
  
  foreach my $page ( 1 .. $in_pdf->pages() ) {
    $out_pdf->import_page($in_pdf, $page, 0);
  }
  $out_pdf->update();
}

closedir $DIR;

[download]

I cannot help but feel I am going about this merging process in a horribly inefficient way (Schlemiel the painter anyone?). Does anyone have any pointers toward a correct/more efficient merging technique?

Thank you for your time.

perl -v

This is perl 5, version 18, subversion 2 (v5.18.2) built for MSWin32-x
+64-multi-thread
(with 1 registered patch, see perl -V for more detail)

Copyright 1987-2013, Larry Wall

Binary build 1802 [298023] provided by ActiveState http://www.ActiveSt
+ate.com
Built Apr 15 2014 10:38:37

[download]
perl -MPDF::API2 -E "say $PDF::API2::VERSION;"
2.023

[download]

Script used to generate the sample PDF files:

<Reveal this spoiler or all in this thread>

In reply to [SOLVED] Problem merging thousands of PDFs with PDF::API2: 'Deep recursion on subroutine "PDF::API2::Basic::PDF::Objind::release"' by ateague

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