Shulou(Shulou.com)06/01 Report--

This article mainly explains "what is Java multithreading and how to create it". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let the editor take you to learn what Java multithreading is and how to create it.

1. Thread pool:

What is a thread pool?

Let's not look at the monologue either. in popular terms, a thread pool is a container for threads, which is taken out of the pool when needed, put back or destroyed when not in use. Such a thread can be used repeatedly, and through this repeated utilization mechanism of threads, the disadvantages caused by creating threads directly can be effectively avoided.

What are the benefits of the thread pool?

Reduced resource consumption (CPU)

Improve the response speed of task execution

Improve the manageability of threads

Thread pool creation flowchart:

In fact, you can see the processing of the thread pool through this diagram:

A new task comes in to determine whether the core thread pool is full. Yes: enter the queue, No: create the task.

Waiting in the queue to determine whether the queue is full, yes: enter the thread pool, No: the task joins the queue

Determine whether the thread pool is full, yes: refuse to execute the task, no: create the thread to execute

2. Create a thread pool:

First, take a look at the creation method given on the official website (part):

Here are four common creation types:

NewCacheThreadPool (create a cacheable thread pool, and new threads will be created only when there are tasks)

NewSingleThreadExecutor (create a single thread pool with only one thread in the pool)

NewFixedThreadPool (int a) (create a thread pool with a fixed number of threads, input parameter: int type)

NewScheduledTreadPool (create a fixed-length thread pool and execute threads in a delayed or timed manner)

1 、 newCacheThreadPool:

Create a cacheable thread object, which means that if the task requires several threads to process, several threads will be created:

The classes that the thread needs to execute:

Public class MyRunnable implements Runnable {int num; public MyRunnable (int num) {this.num = num;} @ Override public void run () {System.out.println (Thread.currentThread (). GetName () + "executed:" + num);}}

Test class:

Public class Test {public static void main (String [] args) {/ / create a single thread pool object with only one thread ExecutorService cachedService = Executors.newCachedThreadPool (); / / perform 5 tasks for (int I = 1; I

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