eval failing to match regex after sometime - regex

Question

I get first input from user which is a tree (having significant height and depth) of nodes. Each of the node contains a regex and modifiers. This tree gets saved in memory. This is taken only once at the application startup.
The second input is a value which is matched starting at the root node of the tree till an exact matching leaf node is found (Depth First Search). The match is determined as follows :
my $evalstr = <<EOEVAL;
if(\$input_value =~ /\$node_regex/$node_modifiers){
1;
}else{
-1;
}
EOEVAL
no strict 'refs';
my $return_value = eval "no strict;$evalstr";
The second input is provided continuously throughout the application's life time by a source.
problem:
The above code works very well for some time (approx. 10 hours), but after continuous input for this time, the eval continuously starts failing and I get -1 in $return_value. All other features of the application work very fine including other comparison statements.If I restart the application, the matching again starts and gives proper results.
Observations:
1) I get deep recursion warning many times, but I read somewhere it is normal as stack size for me would be more than 100 many a times, considering the size of the input tree.
2) If I use simple logic for regex match without eval as above, I don't get any issue for any continuous run of the application.
if($input_value =~ /$node_regex/){
$return_value=1;
}else{
$return_value=-1;
}
but then I have to sacrifice dynamic modifiers, as per Dynamic Modifiers
Checks:
1) I checked $# but it is empty.
2) Also printed the respective values of $input_value,$node_regex and $node_modifiers, they are correct and should have matched the value with regex at the failure point.
3) I checked for memory usage, but it's fairly constant over the time for the perl process.
4) Was using perl 5.8.8 then updated it to 5.12, but still face the same issue.
Question :
What could be the cause of above issue? Why it fails after some time, but works well when the application is restarted?

Answer 1

A definitive answer would require more knowledge of perl internals than I have. But given what you are doing, continuous parsing of large trees, it seems safe to assume that some limit is being reached, some resource is exhausted. I would take a close look at things and make sure that all resources are being released between each iteration of a parse. I would be especially concerned with circular references in the complex structures, and making sure that there are none.