Thanks for your reply, but I don't see any possible memory leakage here. I have attached the code above.. This one blows up with an empty process method ...

Well, in that code, %tmap keeps growing ; %tmap keeps eating memory ; until %tmap has eaten all the memory; does that make sense to you?

... $tmap ... &process(); ...

That looks suspiciously like you're not coping with scoping, subs should take arguments ...

Thanks for your interest. But I am not able to understand what is the meaning of this undef? undef %map I thought that should clear off all the memory!

I tried to push the map inside the while loop, so that the scope itself takes care of things. But, the code still runs out of memory..

while(sysread(CSV, $record, 66)) {
        my $count = 0;
        my %map;
        $map{substr($record, 18, 14)}->{substr($record, 3, 15)} = subs
+tr($record, 36, 29);
        while (sysread(CSV, $record, 66)) {
                $map{substr($record, 18, 14)}->{substr($record, 3, 15)
+} = substr($record, 36, 29);
                if ($count++ > 1000) {
                        $count = 0;
                        last;
                }
        }
        &process(\%map);
}
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