I found that postgres uses different semaphore system call on some different
For example, I found that on linux, System V semaphore (semop etc.) is used
to implement locking, while on Darwin, POSIX semaphore (sem_wait, sem_post
etc.) is used.
linux and Darwin support both System V and POSIX semaphores, i'm wondering
why postgres implement locking using different types of semaphore system
call. Is there any performance or semantic issue on different OSes?