线程池一共是两大类，ForkJoinPool和ThreadPoolExecutor
通过Executors创建的线程池要么是ForkJoinPool，要么就是不同参数值的ThreadPoolExecutor

Executor接口源码
```
public interface Executor {
void execute(Runnable command);
}
```
顶层接口

ExecutorService接口源码
```java public interface ExecutorService extends Executor {

/**
- 不接受新的任务，已接收的任务执行完毕结束 */ void shutdown();
/**
- 立即中断现有执行的线程 */ List shutdownNow();
/**
- Returns {@code true} if this executor has been shut down. *
- @return {@code true} if this executor has been shut down */ boolean isShutdown();
/*
- 要么shutdown调用，要么shutdownNow被调用，否则不会返回true */ boolean isTerminated();
/**
- Blocks until all tasks have completed execution after a shutdown
- request, or the timeout occurs, or the current thread is
- interrupted, whichever happens first.
- 阻塞当前线程，知道下面三者之一发生
- 1.在shutdown()后并且所有任务完成
- 2.指定等待时间超时了
- 3.当前线程被中断了 */ boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException;
/**
- 实际底层还是调用execute(FutureTask) */ Future submit(Callable task);
/**
- */ Future submit(Runnable task, T result);
/**
- submit */ Future<?> submit(Runnable task);
/**
- */ List> invokeAll(Collection<? extends Callable> tasks) throws InterruptedException;
/**
- 所有任务结束后返回 */
  List
  > invokeAll(Collection<? extends Callable
  > tasks,
  long timeout, TimeUnit unit)
  throws InterruptedException;
/* */ T invokeAny(Collection<? extends Callable> tasks) throws InterruptedException, ExecutionException;

/**
- 任意一个任务接收就返回 */
  T invokeAny(Collection<? extends Callable
  > tasks,
```
         long timeout, TimeUnit unit)
```
  throws InterruptedException, ExecutionException, TimeoutException; }

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# AbstractExecutorService抽象类
   - 抽象实现
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## newTaskFor()
```java
   /**
     * 均封装 FutureTask
     *
     */
    protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
        return new FutureTask<T>(runnable, value);
    }
    /**
     * Returns a {@code RunnableFuture} for the given callable task.
     *
     */
    protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
        return new FutureTask<T>(callable);
    }

submit()

submit方法实际也是调用了execute方法 ```java

public Future<?> submit(Runnable task) { if (task == null) throw new NullPointerException(); RunnableFuture ftask = newTaskFor(task, null); *execute(ftask); return ftask; }

public <T> Future<T> submit(Runnable task, T result) {
    if (task == null) throw new NullPointerException();
    RunnableFuture<T> ftask = newTaskFor(task, result);
   *execute(ftask);
    return ftask;
}
public <T> Future<T> submit(Callable<T> task) {
    if (task == null) throw new NullPointerException();
    RunnableFuture<T> ftask = newTaskFor(task);
   *execute(ftask);
    return ftask;
}


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# ThreadPoolExecutor类
具体参数含义之前写过。
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# Executors各种线程池特点
```java
    @Test
    public void testAllPool(){
        // 0队列，0核心线程，MAX_VALUE临时线程,适用于处理时间短但任务多的
        Executors.newCachedThreadPool();
        // 无限队列，5核心 0临时 适用于长任务
        Executors.newFixedThreadPool(5);
        // 无限队列，1核心 0临时 是特殊的FixedThreadPool
        Executors.newSingleThreadExecutor();
        // 延时队列，2核心 MAX_VALUE临时线程，定时任务线程池
        Executors.newScheduledThreadPool(2);
        // 核心线程为1的定时任务线程池
        Executors.newSingleThreadScheduledExecutor();
        // ForkJoinPool
        Executors.newWorkStealingPool();
    }

线程池状态轮转

RUNING->SHUTDOWN：调用了shutdown()
RUNING ->STOP：显式调用shutdownNow()
SHUTDOWN->STOP：显式调用shutdownNow()
SHUTDOWN->TIDYING: 无工作线程和队列为空时
STOP->TIDYING: 无工作线程时
TIDYING->TERMINATED: 调用terminated()方法时

雨润工作笔记

线程池的相关知识

Executor接口源码

ExecutorService接口源码

submit()

线程池状态轮转