How to triger a timer/signal to a running program

[nicholas wang]

Hi,all
  My task is to kill a program when it runs more than a limited time.
  My plat is Linux7.1; I've tried Csh to make it using ps ... ; then kill
this program. But it will get extra  messages to stdout. Of course, use
"limit" command also works. But both are not perfect.
  I know Perl get a command "alarm" will do such a job
  I'm searching a Python counterpart. Does anyone know what it is?
My idea about this job is: ( in a python shell )
  1. mark a signal to a specific program.
  2. run this program
  3. if time exceeds limit(set before run), the shell will kill it.
  2. continue to run the remained commands.

Thanks to you!!