I agree -- you should group your pings using select rather than use a 1-1 thread-ping model. Your thread failure is most likely due to memory issues. By default, threads are allocated a 16MB stack. 100 threads would use more than 1.6GB of memory. If you are really enamored of the thread-per-ping model, and you are using 5.10, you can set the stack size to something reasonable, like 128K (you probably don't need much if all you are doing is a simple ping).

fnord