package com.example.threadpool.service;
import lombok.NonNull;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import java.util.List;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicInteger;
/**
- @program: demo-threadpool
- @description
- @author: tina.liu
- @create: 2022-04-03 20:40
**/
@Slf4j
public class ThreadPoolUtil {
public static final ThreadPoolUtil EXCUTOR = new ThreadPoolUtil();
//核心线程池的数量，同时能够执行的线程数量
private int corePoolSize;
//最大线程池数量，表示当缓冲队列满的时候能继续容纳的等待任务的数量
private int maxPoolSize;
//存活时间
private long keepAliveTime = 1;
private TimeUnit unit = TimeUnit.HOURS;
private ThreadPoolExecutor executor;
private ThreadPoolUtil() {
//给corePoolSize赋值：当前设备可用处理器核心数*2 + 1,能够让cpu的效率得到最大程度执行（有研究论证的）
corePoolSize = Runtime.getRuntime().availableProcessors() * 2 + 1;
maxPoolSize = corePoolSize;
executor = new ThreadPoolExecutor(
//当某个核心任务执行完毕，会依次从缓冲队列中取出等待任务
corePoolSize,
// 然后new LinkedBlockingQueue<Runnable>(),然后maximumPoolSize,但是它的数量是包含了corePoolSize的
maxPoolSize,
//表示的是maximumPoolSize当中等待任务的存活时间
keepAliveTime,
unit,
//缓冲队列，用于存放等待任务，Linked的先进先出
new LinkedBlockingQueue<Runnable>(),
new DefaultThreadFactory(Thread.NORM_PRIORITY, "thread-pool-"),
new ThreadPoolExecutor.AbortPolicy()
);
log.info("Class ThreadPoolUtil field corePoolSize ={},maxPoolSize ={} ", corePoolSize, maxPoolSize);
}
/**
* 执行任务 无返回值
*
* @param runnable
*/
public void execute(Runnable runnable) {
if (runnable != null) {
executor.execute(runnable);
}
}
/**
* 执行任务 有返回值
*
* @param callable
*/
public <T> T executeReturn(Callable<T> callable) {
try {
return executor.submit(callable).get();
} catch (Exception e) {
log.error("Class ThreadPoolUtil executeReturn fail message :{}",e.getMessage());
}
return null;
}
/**
* 执行任务 有返回值
*
* @param callables
*/
public <T> List<Future<T>> executeReturn(List<Callable<T>> callables) {
try {
return executor.invokeAll(callables);
} catch (Exception e) {
log.error("Class ThreadPoolUtil executeReturn fail message :{}",e.getMessage());
}
return null;
}
/**
* 移除任务
*
* @param runnable
*/
public void remove(Runnable runnable) {
if (runnable != null) {
executor.remove(runnable);
}
}
private static class DefaultThreadFactory implements ThreadFactory {
//线程池的计数
private static final AtomicInteger poolNumber = new AtomicInteger(1);
//线程的计数
private final AtomicInteger threadNumber = new AtomicInteger(1);
private final ThreadGroup group;
private final String namePrefix;
private final int threadPriority;
DefaultThreadFactory(int threadPriority, String threadNamePrefix) {
this.threadPriority = threadPriority;
this.group = Thread.currentThread().getThreadGroup();
this.namePrefix = threadNamePrefix + poolNumber.getAndIncrement() + "-thread-";
}
@Override
public Thread newThread(@NonNull Runnable r) {
Thread thread = new Thread(group, r, namePrefix + threadNumber.getAndIncrement(), 0);
// 返回True该线程就是守护线程
// 守护线程应该永远不去访问固有资源，如：数据库、文件等。因为它会在任何时候甚至在一个操作的中间发生中断。
if (thread.isDaemon()) {
thread.setDaemon(false);
}
thread.setPriority(threadPriority);
return thread;
}
}
}
