pcntl_getpriority() gets the priority of pid. If pid is not specified, the pid of the current process is used. Because priority levels can differ between system types and kernel versions, please see your system's getpriority(2) man page for specific details.
pcntl_getpriority() returns the priority of the process or FALSE on error. A lower numerical value causes more favorable scheduling.
process_identifier is one of PRIO_PGRP, PRIO_USER or PRIO_PROCESS.