“ULC Semaphore Requests” reports the number of times a user task was immediately granted a semaphore or had to wait for it. “% of total” shows the percentage of tasks granted semaphores and the percentage of tasks that waited for semaphores as a percentage of the total number of ULC semaphore requests. This is relevant only in SMP environments.
A semaphore is a simple internal locking mechanism that prevents a second task from accessing the data structure currently in use. Adaptive Server uses semaphores to protect the user log caches since more than one process can access the records of a ULC and force a flush.
This category provides the following information:
Granted – The number of times a task was granted a ULC semaphore immediately upon request. There was no contention for the ULC.
Waited – The number of times a task tried to write to ULCs and encountered semaphore contention.
Total ULC Semaphore Requests – The total number of ULC semaphore requests that took place during the interval. This includes requests that were granted or had to wait.
