Get the current wait count of a semaphore.
semaphore-wait-count sem => wait-count
A non negative fixnum.
semaphore-wait-count returns the current number of units that other threads are waiting for from the semaphore sem. The value wait-count is 0 if the semaphore has no thread waiting for it.
The value can change in the semaphore after calling
LispWorks User Guide and Reference Manual - 13 Feb 2015