Can using sem_trywait() cause a deadlock

Question

Can using sem_trywait() let you get into a deadlock or livelock?

Answer 1

If you have multiple threads, nearly any function can participate in a potential livelock or deadlock (or both), depending on how it's used. The algorithm matters. Now, there are certain specific patterns of use of sem_trywait that may or may not be liable to form a live or deadlock, but from just the function name, it's hard to answer with any specificity.

Answer 2

It should fail with E_DEADLK if two threads are contending for the same resource locked by each other's semaphore. This is correct behaviour but you need to detect it and retry if it happens. In other words, yes, it can deadlock, but the system will detect this and fail out of the function rather than leave you hanging.