removed local and every thing worked perfectly

No, it doesn't. The On function sets the signal handler globally, for ever, even after eval has finished. You want local $SIG{'ALRM'} inside that eval.

The extra subs don't make your code any clearer. I think you should keep alarm and local $SIG{'ALRM'} inside the eval.

You could also consider writing a generic timeout function like this:

# untested

sub withTimeout
{
    my ($timeout,$worker,$timeouthandler)=@_;
    eval {
        local $SIG{'ALRM'}=sub { die "TIMEOUT" };
        alarm($timeout);
        $worker->();
        alarm(0);
    };
    if ($@ and $@=~/TIMEOUT/) {
        $timeouthandler->();
    }
}
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Alexander