private boolean addWorker(Runnable firstTask, boolean core) {
        retry:
        for (;;) {
            int c = ctl.get();//獲取當(dāng)前線程池的控制狀態(tài)。
            int rs = runStateOf(c);//獲取當(dāng)前線程池的運(yùn)行狀態(tài)。

            // Check if queue empty only if necessary.
            //下面這個(gè)條件判斷用于判斷線程池是否處于關(guān)閉狀態(tài)，并且任務(wù)隊(duì)列不為空。如果線程池的狀態(tài)大于等于SHUTDOWN，并且不滿足線程池狀態(tài)為SHUTDOWN、首個(gè)任務(wù)為null且任務(wù)隊(duì)列為空的條件，則返回false。這個(gè)判斷是為了確保在線程池關(guān)閉時(shí)，不再添加新的工作線程。
            if (rs >= SHUTDOWN &&
                ! (rs == SHUTDOWN &&
                   firstTask == null &&
                   ! workQueue.isEmpty()))
                return false;

            for (;;) {
                int wc = workerCountOf(c);//獲取當(dāng)前線程池中的工作線程數(shù)量。
                //這個(gè)條件判斷用于判斷工作線程數(shù)量是否達(dá)到上限。如果工作線程數(shù)量大于等于CAPACITY（工作線程數(shù)量的上限）或者大于等于核心線程數(shù)（如果core為true）或最大線程數(shù)（如果core為false），則返回false。這個(gè)判斷是為了確保工作線程數(shù)量不超過(guò)線程池的限制。
                if (wc >= CAPACITY ||
                    wc >= (core ? corePoolSize : maximumPoolSize))
                    return false;
                    //嘗試通過(guò)CAS（比較并交換）操作增加工作線程數(shù)量。如果成功增加工作線程數(shù)量，則跳出循環(huán)，繼續(xù)執(zhí)行后續(xù)邏輯。
                if (compareAndIncrementWorkerCount(c))
                    break retry;
                c = ctl.get();  // 重新讀取當(dāng)前線程池的控制狀態(tài)。
                //再次判斷線程池的運(yùn)行狀態(tài)是否發(fā)生了變化。如果運(yùn)行狀態(tài)發(fā)生了變化，則繼續(xù)重試內(nèi)部循環(huán)。這個(gè)判斷是為了處理在CAS操作過(guò)程中，線程池的狀態(tài)發(fā)生了變化的情況。
                if (runStateOf(c) != rs)
                    continue retry;
                // else CAS failed due to workerCount change; retry inner loop
            }
        }
        ...創(chuàng)建線程的邏輯忽略...
}

final void runWorker(Worker w) {
        Thread wt = Thread.currentThread();
        Runnable task = w.firstTask;
        w.firstTask = null;
        w.unlock(); // allow interrupts
        boolean completedAbruptly = true;
        try {
            while (task != null || (task = getTask()) != null) {
                w.lock();
                // If pool is stopping, ensure thread is interrupted;
                // if not, ensure thread is not interrupted.  This
                // requires a recheck in second case to deal with
                // shutdownNow race while clearing interrupt
                if ((runStateAtLeast(ctl.get(), STOP) ||
                     (Thread.interrupted() &&
                      runStateAtLeast(ctl.get(), STOP))) &&
                    !wt.isInterrupted())
                    wt.interrupt();
                try {
                    beforeExecute(wt, task);
                    Throwable thrown = null;
                    try {
                        task.run();
                    } catch (RuntimeException x) {
                        thrown = x; throw x;
                    } catch (Error x) {
                        thrown = x; throw x;
                    } catch (Throwable x) {
                        thrown = x; throw new Error(x);
                    } finally {
                        afterExecute(task, thrown);
                    }
                } finally {
                    task = null;
                    w.completedTasks++;
                    w.unlock();
                }
            }
            completedAbruptly = false;
        } finally {
            processWorkerExit(w, completedAbruptly);
        }
    }

private Runnable getTask() {
        boolean timedOut = false; // Did the last poll() time out?

        for (;;) {
            int c = ctl.get();
            int rs = runStateOf(c);

            // Check if queue empty only if necessary.
            if (rs >= SHUTDOWN && (rs >= STOP || workQueue.isEmpty())) {
                decrementWorkerCount();
                return null;
            }

            int wc = workerCountOf(c);

            // Are workers subject to culling?
            boolean timed = allowCoreThreadTimeOut || wc > corePoolSize;
			//銷毀線程需要滿足這兩個(gè)條件：1. （允許核心線程銷毀 || 線程數(shù)大于核心線程數(shù)）&& 達(dá)到了銷毀時(shí)間；2. 任務(wù)隊(duì)列中沒(méi)有任務(wù)了
            if ((wc > maximumPoolSize || (timed && timedOut)) 
                && (wc > 1 || workQueue.isEmpty())) {
                if (compareAndDecrementWorkerCount(c))
                // 這里返回了null，外層方法就跳出了while循環(huán)，從而結(jié)束該線程
                    return null;
                continue;
            }

            try {
            // 超時(shí)時(shí)間就是在這里設(shè)置的，如果允許超時(shí)銷毀，那么就用poll進(jìn)行拉取任務(wù)，超過(guò)了keepAliveTime就返回null。take是阻塞性等待
                Runnable r = timed ?
                    workQueue.poll(keepAliveTime, TimeUnit.NANOSECONDS) :
                    workQueue.take();
                if (r != null)
                    return r;
                timedOut = true;
            } catch (InterruptedException retry) {
                timedOut = false;
            }
        }
    }