in reply to
Looking for a string from a huge log file
Your example leaves a little to be desired -- in order for monks to be able diagnose your issue, we need to be able to replicate it. This means providing some sample input and expected output in addition to code that displays this issue. See How do I post a question effectively?.
The problem you are describing is frequently caused by a variable that gets set in a loop, and then not cleared before it goes into another instance of that loop; this type of issue can usually be addressed with tight scoping of variables combined with the strict pragma. If I assume the code you posted occurs in a loop over a number of files, I'd expect including something like undef $message_1; at the end of your code might resolve your issue. But this is all conjecture without an effective problem statement.
#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.