Class QueueingThreadPoolExecutor

  • All Implemented Interfaces:
    Executor, ExecutorService

    public class QueueingThreadPoolExecutor
    extends ThreadPoolExecutor
    This is a thread pool executor service, which works as a developer would expect it to work. The default ThreadPoolExecutor does the following (see the official JavaDoc):
    • If fewer than corePoolSize threads are running, the Executor always prefers adding a new thread rather than queuing.
    • If corePoolSize or more threads are running, the Executor always prefers queuing a request rather than adding a new thread.
    • If a request cannot be queued, a new thread is created unless this would exceed maximumPoolSize, in which case, the task will be rejected.
    This class in contrast implements the following logic:
    • corePoolSize is 1, so threads are only created on demand
    • If the number of busy threads is smaller than the threadPoolSize, the Executor always prefers adding (or reusing) a thread rather than queuing it.
    • If threadPoolSize threads are busy, new requests will be put in a FIFO queue and processed as soon as a thread becomes idle.
    • The queue size is unbound, i.e. requests will never be rejected.
    • Threads are terminated after being idle for at least 10 seconds.
    Please note that this implementation (with its partially hard-coded settings) is specifically targeted for use on embedded devices without a high throughput. If you intend to use it for mass data processing on a server, you should definitely tweak those settings.
    Author:
    Kai Kreuzer - Initial contribution