java循环中开启线程池 线程池循环提交任务

public void execute(Runnable command) {
        if (command == null)
            throw new NullPointerException();
        
        int c = ctl.get();
        if (workerCountOf(c) < corePoolSize) { // 如果线程数小于corePoolSize则创建新线程
            if (addWorker(command, true))
                return;
            c = ctl.get();
        }
        if (isRunning(c) && workQueue.offer(command)) { // 如果线程数大于等于corePoolSize则尝试把线程放进阻塞队列中
            int recheck = ctl.get();
            if (! isRunning(recheck) && remove(command))
                reject(command);
            else if (workerCountOf(recheck) == 0)
                addWorker(null, false);
        }
        else if (!addWorker(command, false)) // 放入队列失败尝试创建新线程
            reject(command); // 线程数大于maxPoolSize时调用拒绝策略
    }

  提交任务的过程可以总结为：如果线程数没达到corePoolSize则创建线程，如果达到了且阻塞队列未满则放入阻塞队列，如果队列满了且在线程数没达到maxPoolSize会创建先线程，如果以上条件都不满足则调用拒绝策略。
  提交时用到的addWorker()函数：

private boolean addWorker(Runnable firstTask, boolean core) {
        retry:
        for (;;) {
            int c = ctl.get();
            int rs = runStateOf(c);

            // 检查线程池是否进入关闭状态或者阻塞队列非空
            if (rs >= SHUTDOWN &&
                ! (rs == SHUTDOWN &&
                   firstTask == null &&
                   ! workQueue.isEmpty()))
                return false;

            for (;;) {
                int wc = workerCountOf(c);
                if (wc >= CAPACITY ||
                    wc >= (core ? corePoolSize : maximumPoolSize))
                    // 线程数超过corePoolSize或maxPoolSize则不会开启新线程
                    return false;
                if (compareAndIncrementWorkerCount(c)) // CAS将任务数+1成功以后跳出循环
                    break retry;
                c = ctl.get();           // 再次获取线程池的状态
                if (runStateOf(c) != rs) //如果状态发生改变则再次循环
                    continue retry;
            }
        }
        
        boolean workerStarted = false;
        boolean workerAdded = false;
        Worker w = null;
        try {
            w = new Worker(firstTask); // 创建线程
            final Thread t = w.thread;
            if (t != null) {
                final ReentrantLock mainLock = this.mainLock;
                mainLock.lock();
                try {
                    // Recheck while holding lock.
                    // Back out on ThreadFactory failure or if
                    // shut down before lock acquired.
                    int rs = runStateOf(ctl.get());

                    if (rs < SHUTDOWN ||
                        (rs == SHUTDOWN && firstTask == null)) { // 检查线程池状态
                        if (t.isAlive()) // precheck that t is startable
                            throw new IllegalThreadStateException();
                        workers.add(w); // 添加线程
                        int s = workers.size();
                        if (s > largestPoolSize)
                            largestPoolSize = s;
                        workerAdded = true;
                    }
                } finally {
                    mainLock.unlock();
                }
                if (workerAdded) {
                    t.start();  // 加入成功后则启动
                    workerStarted = true;
                }
            }
        } finally {
            if (! workerStarted) // 加入失败将workCount-1
                addWorkerFailed(w);
        }
        return workerStarted;
    }

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