How to set timer in perl

Rahul Gupta has asked for the wisdom of the Perl Monks concerning the following question:

Hi ,

I have a file with huge data, i read the same file and stored the content in an array

my @file_content = read(file);
foreach(@file_content){
 if ($_ =~ m/somestring/){
 }
}
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i have to check the string for some specific time(i.e 5 secs..). if i don't get the string in defined time, then it should get terminate.

i used alarm but it didn't work for me.

can any one help me

thanks in advance