What is java thread pool

What is Java’s thread pool, what are its types, and what are their functions                                                                                                                                 # #)

Thread pool is a form of multi-thread processing. Tasks are added to the queue during processing, and then these tasks are automatically started after the threads are created. Each thread uses the default stack size to Running at the default priority and in a multi-threaded apartment, if a thread is idle in managed code, the thread pool will insert another worker thread to keep all processors busy.

If all thread pools remain busy at all times, but the queues contain pending work, the thread pool will never exceed the maximum number of worker threads after a period of time. Threads that exceed the maximum can be queued, but they cannot be started until other threads have finished.

The top-level interface of the thread pool in java is Executor. Executor is not a thread pool, but just a tool for executing threads, and the real thread pool is ExecutorService.

What are the thread pools in java?

1.newCachedThreadPool creates a cacheable thread pool process

2.newFixedThreadPool creates a fixed-length thread pool

3.newScheduledThreadPool creates a fixed-length thread pool

4.newSingleThreadExecutor creates a single-threaded thread pool

The following is analyzed one by one:

newCachedThreadPool,

is a A thread pool with a variable number of threads, and its maximum number of threads is Integer.MAX_VALUE. This number is very large. A cacheable thread pool. If the length of the thread pool exceeds processing needs, idle threads can be flexibly recycled. If there is no recycling, then Create a new thread. However, idle threads in the thread pool have timeout limits. This timeout is 60 seconds. If idle threads exceed 60 seconds, they will be recycled. Calling execute will reuse the previously constructed thread (if the thread is available). This type of thread pool is more suitable for executing a large number of less time-consuming tasks. When the entire thread pool is idle, the threads in the thread pool will time out and be stopped.

newFixedThreadPool

Create a thread pool with a specified number of worker threads. A worker thread is created whenever a task is submitted. When threads are idle, they will not be recycled unless the thread The pool is closed. If the number of worker threads reaches the initial maximum number of thread pools, the submitted tasks will be stored in the pool queue (no size limit). Since newFixedThreadPool only has core threads and these core threads will not be recycled, it can respond to external requests more quickly.

newScheduledThreadPool

Create a thread pool whose number of core threads is fixed, but the number of non-core threads is unlimited, and when non-core threads are idle, they will be recycled immediately. Commands can be scheduled to run after a given delay or periodically. This type of thread pool is mainly used to execute scheduled tasks and recurring tasks with a fixed period.

newSingleThreadExecutor

This type of thread pool has only one core thread inside, which is executed in an unbounded queue. This eliminates the need to deal with thread synchronization issues between these tasks. It ensures that all Tasks are executed sequentially on the same thread, and no more than one thread may be active at any given time.

The above is the detailed content of What is java thread pool. For more information, please follow other related articles on the PHP Chinese website!