[hornetblack]

If you had a Green threaded program and one of the threads segfaulted. You would probably want to catch Segv and kill that thread. (Not killing the OS thread running it).

I've also seen is used to implement a distributed malloc. When a segfault occurs, the handler messages the programs peers asking if they have the data for that address. If so the peers sends the page and the handler maps in a new page for that address with the correct data in it. This is essentially implementing a page fault handler in user space. (For some network backed memory).

[gpderetta]

Why would you only want to kill that green thread? On any thread implementation I'm aware of, an unhandled segfault kills the whole process. Anything else is disaster waiting to happen.