Semaphore
Related Docs:
object Semaphore
| package util
the task to run once permits are available
a future that completes once permitCount permits are available AND task completes. task is started once permitCount permits are available. The permits are removed from the pool while task is running and after task completes the permits are returned to the pool.
java.lang.IllegalArgumentException if the number of requested permits
exceeds maxAvailablePermits
the current number of permits available
the maximum number of permits in the pool
the count of callers currently waiting on permits to become available
A trait for a non-blocking semaphore that ensures limiting concurrent execution to tasks that have been granted the requested number of permits from a limited pool of permits. The acquire method is used to request the execution of a task once the requested number of permits become available. If the permits are not immediately available, the request is placed into a FIFO queue while waiting for permits to become available. The permit pool size is typically static with permits released back to the pool upon completion of tasks. However, some implementations may have dynamic sized pools that expend permits instead of releasing them, replenishing permits through some other mechanism.
Note1: Because Semaphore accepts a function to the task to run, it is not possible for callers to double lock, double release or forget to release permits. Note2: Semaphore is NOT reentrant Note3: Semaphore should never be used when other options make more sense. Semaphore is designed for synchronizing many tasks (100+) and/or long running tasks (10ms+). Unlike other options, Semaphore does not block and consume a thread while waiting for permits to become available. However, Semaphore is not the most performant option.