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

Hey Thank you.My problem is ,I want subs to switch on and off my alarm so that i can call them when needed. Any suggestion how to do that ?

I want subs to switch on and off my alarm so that i can call them when needed

Why? The code you showed first is more or less the usual code for having a timeout in some long running code. (You do know the example in perlipc, right?) If you don't need a timeout, just don't mess with alarm and $SIG{'ALRM'} at all.

In code:

withTimeout(30,\&doSomething,sub { die 'Oooops, doSomething was too sl
+ow' }); # <-- timeout after 30 seconds
doSomething(); # <-- no timeout here
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If you still think that you need to "switch on and off", please explain your actual problem.

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)