A thread pool optimised for bursts of activity.
Designed for the following use-case: A single thread produces work which must then be performed by a pool of worker threads. The work is produced infrequently, but in bursts. Under normal operation, therefore, the threads in the pool sleep until some event requires many of them to be suddenly be woken at once. Those threads perform some work before going back to sleep again.
See the documentation for details.