I've got a web server that's being spidered every few daysbut I've noticed a problem on a few occasions. Esentially the CPU usage jumps to 90%+ and memory usage increases. Eventually all of the swap memory is used up and the server crashes when the process has run for 30 or 40 mins.

Are there any perl / bash scripts that can detect processes that have used over xx% of cpu time or have been running for more than xx mins and kill them or restart the parent process?

Yes, their are scripts that will do this. I can not provide any actual URL's or threads. But I know it has been discussed before. You may want to try doing a search. I am positive you will find more then one thing relating to what your trying to find. Good Luck.