Wakes one thread waiting on a given condition-variable.
condition-variable-signal wakes exactly one thread waiting on the condition-variable condvar. In most uses of condition variables, the caller should be holding the lock that the waiter used when calling condition-variable-wait for condvar, but this is not required. When using the lock, you may prefer to use lock-and-condition-variable-signal.
LispWorks User Guide and Reference Manual - 20 Sep 2017