1. A method of assuring thread rendezvous for a plurality of threads executing in a computer system, wherein said method comprises: generating an instruction at a plurality of points in one or more code portions which can each be executed by one or more threads, wherein said instruction is a light-weight instruction and does not cause a trap when executed; causing each instance of said instruction to become a trapping instruction, wherein when said trapping instruction is executed by a thread, a trap is caused and the execution of said thread is suspended; and determining whether execution of all threads have been suspended after causing each instance of said instruction to become a trapping instruction.