Another simple method is to use select, ie:

select(undef undef undef, 2);
[download]

You can also use signals:

eval
{
   local $SIG{'ALRM'} = sub{die 'timesup';};
   alarm 2;
   # Now do something as a pause
  while(1)
  {
    select(undef,undef,undef,0.01);
  }
  alarm 0;
};
if($@ =~ 'timesup')
{
  # Call timeout code
}
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On the face of it, you gain nothing in the second example. However, you can use this to timeout pieces of code should you not want to hang around forever. Gaining a lock on a file for example.

There are some platform issues using SIG{ALRM}, alarm() and select() but you should be ok on most platforms.

HTH
Simon

PS: I was eating toast when I posted this so please excuse any typos :P