highload system:
when I run this script:
for($i = 0; $i < 20000; $i++){
      $semid = sem_get (  0xf01, 1, 0666 );
	  
      if ( !$semid ) {
         echo "mem.mem: Can't get semaphore<BR>";
         return;
      }
      if ( !sem_acquire( $semid ) ) {
         echo "mem.mem: Can't acquire semaphore<BR>";
         return;
      }
      if( !sem_release( $semid ) ) {
         echo "mem: Can't release semaphore";
      }
}

shell is return:

semop() failed acquiring SYSVSEM_SETVAL for key 0xf01: Numerical result out of range