Locks limit the number of jobs that access the same resources, e.g. databases, in parallel. Locks allow mutual exclusive access, i.e. jobs wait without any consumption of CPU for a lock to be released.
Use of Locks
- Locks in the JobScheduler prevent the execution of a job, as long as a particular lock has been acquired by one or more other jobs. Locks are available for individual jobs and for jobs in job chains. Should a job be waiting for a lock to be released (lock contention), then it will be automatically started as soon as the lock has been released. In the mean time no resources such as CPU or memory are consumed by job waiting for a lock.
- For a lock you configure how many jobs could use the lock non-exclusively, i.e. in parallel.
- A job can acquire multiple locks and can use them in exclusive or non-exclusive mode.
- If a lock is used non-exclusively then other jobs that use the same lock can start in parallel until the maximum number of non-exclusive jobs is reached.
- If a job uses the lock in exclusive mode then other jobs with the same lock have to wait until the lock is released.