Thank you for your reply.

The first part of the code is at the highest level of the program, so @input is used throughout the while loop, which basically is the whole program. The first part just opens a file with website-addresses which get loaded into @input and then the loop cycles through them.

In any case, I have now changed the code to the following:

use warnings;
use strict;
use diagnostics;
use HTML::FormatText;
use HTML::TreeBuilder 5 - weak;
open INPUT, "< D:/websitelocations.txt" or die "Problem: $!";
my @INPUT=<INPUT>;
close INPUT;
while (@INPUT) {
 my $input=shift(@INPUT);   
 chomp $input;
 print $input;
 my $content=HTML::FormatText->format_file($input, leftmargin => 0, ri
+ghtmargin => 50);
 # followed by regular expressions, the results of which are saved pri
+nted into a new file, all of this is currently disabled
 }
[download]

The memory leak is still there though. It runs out of memory after about 3000 files, but I have more than 28 000.

I still think it has something to do with HTML::FormatText. I read elsewhere that this calls HTML::Treebuilder which in the past has caused memory leaks when the object was not explicitly deleted. I added now

which should take care of it according to CPAN documentation on HTML::TreeBuilder. However, apparently it does not. I also tried to add explicit calls to the delete function:

As well as

But this just gives me an error message: can't locate object message

What is  $content->delete(new) supposed to be or do (what is the string "new") ?

Nevermind

here is my tip, do a Data::Dumper of an object afer one or 10 files, and look for references

Note especially the bless'ed package names

Then go write some destructors, its what I did for bugs in HTML::TableExtract/HTML::TableExtract Memory Usage

Since you're using sub format_file { I'd copy/paste its source and Dumper the objects involved to find circular-references $VAR1 = { ... \$VAR1 };

The following code (adding the delete command in the eval call) works (no error message: "can't call method..."), but there is still a memory leak.

use warnings;
use strict;
use diagnostics;
use HTML::FormatText;
use HTML::TreeBuilder 5 - weak;
use constant HAS_LEAKTRACE => eval{ require Test::LeakTrace };
use Test::More HAS_LEAKTRACE ? (tests => 1) : (skip_all => 'require Te
+st::LeakTrace');
use Test::LeakTrace;
leaks_cmp_ok{
open INPUT, "< D:/websiteadresses.txt" or die "Problem: $!";
# The file contains the adresses of 28 000 websites
my @INPUT=<INPUT>;
close INPUT;
while (@INPUT) {
 my $input=shift(@INPUT);   
 #my $proposal;
 chomp $input;
 print $input;
 my $content=HTML::FormatText->format_file($input, leftmargin => 0, ri
+ghtmargin => 50);
 eval { $content->delete; };
 # followed by regular expressions, the results of which are saved in 
+a different file - all now disabled
 }
} '<', 1;
[download]

Sorry, my mistake, this was supposed to read

$content->delete();

The hope was that this would destroy the Treebuilder object, which apparently gets build via HTML::FormatText, and thus prevent the memory leak. There is a reference to a delete function in the CPAN documentation, but I just get the error message "Can't call method...". The same goes for this line, which I just tried now after reading your earlier entry:

$content->eof;

In my reading of the CPAN documentation of Data::Dumper (not pretending that I understood most of it...) I would need to know the variable names that I am tracking first. But I guess my problem is exactly that I do not know them. It seems that HTML::TreeBuilder is creating something in the background.

I do not think that this is what you were suggesting, but I tried the following code:

use warnings;
use strict;
use diagnostics;
use HTML::FormatText;
use Data::Dumper;
open INPUT, "< D:/websiteadresses.txt" or die "Problem: $!";
my @INPUT=<INPUT>;
close INPUT;
while (@INPUT) {
 my $inputfile=shift(@INPUT);   
  chomp $inputfile;
 my $content=HTML::FormatText->format_from_file($inputfile);
 print Dumper($_, $´);
}
[download]

The output is $var1=undef; and $var2=undef; - no problem there I guess...

Thank you for pointing out Test::LeakTrace. I have tried this now, using the code from the CPAN example, but I do not receive any report.

use warnings;
use strict;
use diagnostics;
use HTML::FormatText;
use HTML::TreeBuilder 5 - weak;
use constant HAS_LEAKTRACE => eval{ require Test::LeakTrace };
use Test::More HAS_LEAKTRACE ? (tests => 1) : (skip_all => 'require Te
+st::LeakTrace');
use Test::LeakTrace;
leaks_cmp_ok{
open INPUT, "< D:/websiteadresses.txt" or die "Problem: $!";
#The file contains 28000 addresses of websites (each one on a new line
+)
my @INPUT=<INPUT>;
close INPUT;
while (@INPUT) {
 my $input=shift(@INPUT); 
  chomp $input;
 print $input;
 my $content=HTML::FormatText->format_file($input, leftmargin => 0, ri
+ghtmargin => 50);
 # This is followed by regular expressions, the results of which are s
+aved in a new file; all of this is disabled now.
 }
} '<', 1;
[download]

The program just runs out of memory after about 3000 runs through the while-loop, but the program output is not followed by any report from LeakTrace. I also did not see a reference to a file in which the report is saved, etc. on the CPAN documentation for Leaktrace. Not sure what to do now...

I am running this in ActiveState's Komodo, but there is not output from Leaktrace either in the internal output window in Komodo nor in the external shell

LeakTrace: I now found the following comment in the overall output (just not at the very end, where I expected it):

"Looks like your test exited with 1 before it could output anything"