Threads The following are exported by the THREADS structure. (WITH-MULTITASKING thunk) Initializes for multitasking, then starts up a thread for the execution of . That thread and all others created will run in the dynamic context of the call to with-multitasking. The call to with-multitasking finally returns only when the scheduler runs out of things to do. (SPAWN thunk) => thread Create and schedule a new thread that will execute . (MAKE-LOCK) => lock (WITH-LOCK lock thunk) => whatever returns (OBTAIN-LOCK lock) (RELEASE-LOCK lock) Locks are semaphores. (MAKE-CONDVAR) => condvar (CONDVAR-REF condvar) => value of condvar (CONDVAR-SET! condvar value) Condition variables. Attempts to reference a condition variable before it has been set cause the referencing thread to block. Setting a condition variable to two different values is an error. (RELINQUISH-TIMESLICE) Let other threads run for a while. ONE-SECOND The number of time units in one second. (SLEEP time) Sleep for