Hi PerlMonks,

I have a question about Perl and the way it handles RAM with the regex binding operator (=~).

Preface: I am running Debian Squeeze with 1024mb of RAM; My perl version is 5.10.1; I have chosen not to upgrade my RAM;

Note: I think that it is important to mention that the string I wish to do a global match for is in the area of 50mb. :(

Problem: I am attempting to return an array from a global match on a very large string (my @array = $somebigstring =~ /regex/g) but it eats up (in my understanding) far more memory than it should.

My (failing) Solutions: I have used undef() on both $somebigstring and @array, which frees a an amount of memory more or less equal to their size. This still leaves nearly all of my RAM taken up by some unknown data.
Writing the data to a file, then processing it line by line

My Thoughts: I believe that the binding operator may set some small variables for each match. These small variable's collective size becomes very large if many matches are made, as in a global match.

Are my assumptions correct, and if so is there a nice way to tell perl to release or not store that "extra" data? I am aware that perl has a memory "pool" that does not release memory to the OS until the script is over.

I will provide a code snippet below, and would like any suggestions on how to handle the memory hogging.

print "\tProcessing data...\n";
foreach (@links) {
    my $link = $_;
    
    # Get data from the internet
    my $httpReply = $browser->get($link);
    
    ####### This is my problem, the regex match eats up a lot of RAM.
    my @data = $httpReply->content =~ /regex/g;
    undef($httpReply); #Frees memory round the size of the webpage.
    #undef(@data); #Frees memory around the size of the array.
    #######

    ####### If the RAM is nearly full, I am unable to completely store
+ the values in a hash.
    # Add each extracted data to the hash
    while(scalar @data) {
        my $line = shift(@data);
        my ($field1, $field2) = split(':', lc($line));

        # Sort the emails into a hash of arrays. key = domain; value =
+ [username, reference]    
        push(@{$emailHash{$field2}} , [$field1, $link]);            
    }
}

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In reply to Binding operator RAM eater by techtruth

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