線程與線程池的那些事之線程池篇（萬字長文）

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是頂級接口，裏面只有一個方法","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"execute(Runnable command)","attrs":{}}],"attrs":{}},{"type":"text","text":"，定義的是調度線程池來執行任務，它定義了線程池的基本規範，執行任務是它的天職。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"ExecutorService","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"ExecutorService","attrs":{}}],"attrs":{}},{"type":"text","text":" 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this.result = result;\n }\n public T call() {\n task.run();\n // 返回傳入的結果\n return result;\n }\n }\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"還有一個方法值得一提：","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"invokeAny()","attrs":{}}],"attrs":{}},{"type":"text","text":": 在 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"ThreadPoolExecutor","attrs":{}}],"attrs":{}},{"type":"text","text":"中使用","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"ExecutorService","attrs":{}}],"attrs":{}},{"type":"text","text":" 中的方法 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"invokeAny()","attrs":{}}],"attrs":{}},{"type":"text","text":" 取得第一個完成的任務的結果，當第一個任務執行完成後，會調用 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定義的是線程池的一些操作，包括關閉，判斷是否關閉，是否停止，提交任務，批量提交任務等等。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"AbstractExecutorService","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"AbstractExecutorService","attrs":{}}],"attrs":{}},{"type":"text","text":" 是一個抽象類，實現了 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(定時任務有其他的接口)，我們最最常用的就是","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"ThreadPoolExecutor","attrs":{}}],"attrs":{}},{"type":"text","text":"。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/44/4482409d96ebfd2488372d3f1fba0587.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"ThreadPoolExecutor","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"重點來了!!!","attrs":{}},{"type":"text","text":" ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"ThreadPoolExecutor","attrs":{}}],"attrs":{}},{"type":"text","text":" 一般就是我們平時常用到的線程池類，所謂創建線程池，如果不是定時線程池，就是使用它。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"先看","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"ThreadPoolExecutor","attrs":{}}],"attrs":{}},{"type":"text","text":"的內部結構(屬性)：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"public class ThreadPoolExecutor extends AbstractExecutorService {\n // 狀態控制，主要用來控制線程池的狀態，是核心的遍歷，使用的是原子類\n private final AtomicInteger ctl = new AtomicInteger(ctlOf(RUNNING, 0));\n // 用來表示線程數量的位數（使用的是位運算，一部分表示線程的數量，一部分表示線程池的狀態）\n // SIZE = 32 表示32位，那麼COUNT_BITS就是29位\n private static final int COUNT_BITS = Integer.SIZE - 3;\n // 線程池的容量，也就是27位表示的最大值\n private static final int CAPACITY = (1 << COUNT_BITS) - 1;\n\n // 狀態量，存儲在高位，32位中的前3位\n // 111（第一位是符號位，1表示負數），線程池運行中\n private static final int RUNNING = -1 << COUNT_BITS; \n // 000\n private static final int SHUTDOWN = 0 << COUNT_BITS;\n // 001\n private static final int STOP = 1 << COUNT_BITS;\n // 010\n private static final int TIDYING = 2 << COUNT_BITS;\n // 011\n private static final int TERMINATED = 3 << COUNT_BITS;\n\n // 取出運行狀態\n private static int runStateOf(int c) { return c & ~CAPACITY; }\n // 取出線程數量\n private static int workerCountOf(int c) { return c & CAPACITY; }\n // 用運行狀態和線程數獲取ctl\n private static int ctlOf(int rs, int wc) { return rs | wc; }\n \n // 任務等待隊列\n private final BlockingQueue workQueue;\n // 可重入主鎖（保證一些操作的線程安全）\n private final ReentrantLock mainLock = new ReentrantLock();\n // 線程的集合\n private final HashSet workers = new HashSet();\n \n // 在Condition中，用await()替換wait()，用signal()替換notify()，用signalAll()替換notifyAll()，\n // 傳統線程的通信方式，Condition都可以實現，Condition和傳統的線程通信沒什麼區別，Condition的強大之處在於它可以爲多個線程間建立不同的Condition\n private final Condition termination = mainLock.newCondition();\n \n // 最大線程池大小\n private int largestPoolSize;\n // 完成的任務數量\n private long completedTaskCount;\n // 線程工廠\n private volatile ThreadFactory threadFactory;\n // 任務拒絕處理器\n private volatile RejectedExecutionHandler handler;\n // 非核心線程的存活時間\n private volatile long keepAliveTime;\n // 允許核心線程的超時時間\n private volatile boolean allowCoreThreadTimeOut;\n // 核心線程數\n private volatile int corePoolSize;\n // 工作線程最大容量\n private volatile int maximumPoolSize;\n // 默認的拒絕處理器（丟棄任務）\n private static final RejectedExecutionHandler defaultHandler =\n new AbortPolicy();\n // 運行時關閉許可\n private static final RuntimePermission shutdownPerm =\n new RuntimePermission(\"modifyThread\");\n // 上下文\n private final AccessControlContext acc;\n // 只有一個線程\n private static final boolean ONLY_ONE = true;\n}\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"線程池狀態","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"從上面的代碼可以看出，用一個32位的對象保存線程池的狀態以及線程池的容量，高3位是線程池的狀態，而剩下的29位，則是保存線程的數量：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":" // 狀態量，存儲在高位，32位中的前3位\n // 111（第一位是符號位，1表示負數），線程池運行中\n private static final int RUNNING = -1 << COUNT_BITS; \n // 000\n private static final int SHUTDOWN = 0 << COUNT_BITS;\n // 001\n private static final int STOP = 1 << COUNT_BITS;\n // 010\n private static final int TIDYING = 2 << COUNT_BITS;\n // 011\n private static final int TERMINATED = 3 << COUNT_BITS;\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"各種狀態之間是不一樣的，他們的狀態之間變化如下：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/8d/8d9dae20a9436627fe9465b0a9a43108.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"RUNNING：運行狀態，可以接受任務，也可以處理任務","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"SHUTDOWN：不可以接受任務，但是可以處理任務","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"STOP：不可以接受任務，也不可以處理任務，中斷當前任務","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"TIDYING：所有線程停止","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"TERMINATED：線程池的最後狀態","attrs":{}}]}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"Worker 實現","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"線程池，肯定得有池子，並且是放線程的地方，在 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"ThreadPoolExecutor","attrs":{}}],"attrs":{}},{"type":"text","text":" 中表現爲 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Worker","attrs":{}}],"attrs":{}},{"type":"text","text":"，這是內部類：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/01/011a2f829b87221becdb7b9dd50f7c1a.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"線程池其實就是 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Worker","attrs":{}}],"attrs":{}},{"type":"text","text":" (打工人，不斷的領取任務，完成任務)的集合，這裏使用的是 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"HashSet","attrs":{}}],"attrs":{}},{"type":"text","text":":","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"private final HashSet workers = new HashSet();\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"Worker","attrs":{}}],"attrs":{}},{"type":"text","text":" 怎麼實現的呢？","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"Worker","attrs":{}}],"attrs":{}},{"type":"text","text":" 除了繼承了 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"AbstractQueuedSynchronizer","attrs":{}}],"attrs":{}},{"type":"text","text":",也就是 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"AQS","attrs":{}}],"attrs":{}},{"type":"text","text":" ， ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"AQS","attrs":{}}],"attrs":{}},{"type":"text","text":" 本質上就是個隊列鎖，一個簡單的互斥鎖，一般是在中斷或者修改 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"worker","attrs":{}}],"attrs":{}},{"type":"text","text":" 狀態的時候使用。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"內部引入","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"AQS","attrs":{}}],"attrs":{}},{"type":"text","text":"，是爲了線程安全，線程執行任務的時候，調用的是","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"runWorker(Worker w)","attrs":{}}],"attrs":{}},{"type":"text","text":"，這個方法不是worker的方法，而是 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"ThreadPoolExecutor","attrs":{}}],"attrs":{}},{"type":"text","text":"的方法。從下面的代碼可以看出，每次修改","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Worke","attrs":{}}],"attrs":{}},{"type":"text","text":"r的狀態的時候，都是線程安全的。","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Worker","attrs":{}}],"attrs":{}},{"type":"text","text":"裏面，持有了一個線程","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Thread","attrs":{}}],"attrs":{}},{"type":"text","text":",可以理解爲是對線程的封裝。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"至於","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"runWorker(Worker w)","attrs":{}}],"attrs":{}},{"type":"text","text":"是怎麼運行的？先保持這個疑問，後面詳細講解。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":" // 實現 Runnable，封裝了線程\n private final class Worker\n extends AbstractQueuedSynchronizer\n implements Runnable\n {\n // 序列化id\n private static final long serialVersionUID = 6138294804551838833L;\n\n // worker運行的線程\n final Thread thread;\n \n // 初始化任務，有可能是空的，如果任務不爲空的時候，其他進來的任務，可以直接運行，不在添加到任務隊列\n Runnable firstTask;\n // 線程任務計數器\n volatile long completedTasks;\n\n // 指定一個任務讓工人忙碌起來，這個任務可能是空的\n Worker(Runnable firstTask) {\n // 初始化AQS隊列鎖的狀態\n setState(-1); // 禁止中斷直到 runWorker\n this.firstTask = firstTask;\n // 從線程工廠，取出一個線程初始化\n this.thread = getThreadFactory().newThread(this);\n }\n\n // 實際上運行調用的是runWorker\n public void run() {\n // 不斷循環獲取任務進行執行\n runWorker(this);\n }\n\n // 0表示沒有被鎖\n // 1表示被鎖的狀態\n protected boolean isHeldExclusively() {\n return getState() != 0;\n }\n // 獨佔，嘗試獲取鎖，如果成功返回true，失敗返回false\n protected boolean tryAcquire(int unused) {\n // CAS 樂觀鎖\n if (compareAndSetState(0, 1)) {\n // 成功，當前線程獨佔鎖\n setExclusiveOwnerThread(Thread.currentThread());\n return true;\n }\n return false;\n }\n // 獨佔方式，嘗試釋放鎖\n protected boolean tryRelease(int unused) {\n setExclusiveOwnerThread(null);\n setState(0);\n return true;\n }\n // 上鎖，調用的是AQS的方法\n public void lock() { acquire(1); }\n // 嘗試上鎖\n public boolean tryLock() { return tryAcquire(1); }\n // 解鎖\n public void unlock() { release(1); }\n // 是否鎖住\n public boolean isLocked() { return isHeldExclusively(); }\n\n // 如果開始可就中斷\n void interruptIfStarted() {\n Thread t;\n if (getState() >= 0 && (t = thread) != null && !t.isInterrupted()) {\n try {\n t.interrupt();\n } catch (SecurityException ignore) {\n }\n }\n }\n }\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"任務隊列","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"除了放線程池的地方，要是任務很多，沒有那麼多線程，肯定需要一個地方放任務，充當緩衝作用，也就是任務隊列，在代碼中表現爲：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"private final BlockingQueue workQueue;\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"拒絕策略和處理器","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"計算機的內存總是有限的，我們不可能一直往隊列裏面增加內容，所以線程池爲我們提供了選擇，可以選擇多種隊列。同時當任務實在太多，佔滿了線程，並且把任務隊列也佔滿的時候，我們需要做出一定的反應，那就是拒絕還是拋出錯誤，丟掉任務？丟掉哪些任務，這些都是可能需要定製的內容。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"如何創建線程池","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"關於如何創建線程池，其實 ","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"ThreadPoolExecutor","attrs":{}}],"attrs":{}},{"type":"text","text":"提供了構造方法，主要參數如下，不傳的話會使用默認的：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"核心線程數：核心線程數，一般是指常駐的線程，沒有任務的時候通常也不會銷燬","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"最大線程數：線程池允許創建的最大的線程數量","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"非核心線程的存活時間：指的是沒有任務的時候，非核心線程能夠存活多久","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"時間的單位：存活時間的單位","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"存放任務的隊列：用來存放任務","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"線程工廠","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"拒絕處理器:如果添加任務失敗，將由該處理器處理","attrs":{}}]}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":" // 指定核心線程數，最大線程數，非核心線程沒有任務的存活時間，時間單位，任務隊列 \n public ThreadPoolExecutor(int corePoolSize,\n int maximumPoolSize,\n long keepAliveTime,\n TimeUnit unit,\n BlockingQueue workQueue) {\n this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,\n Executors.defaultThreadFactory(), defaultHandler);\n }\n // 指定核心線程數，最大線程數，非核心線程沒有任務的存活時間，時間單位，任務隊列，線程池工廠 \n public ThreadPoolExecutor(int corePoolSize,\n int maximumPoolSize,\n long keepAliveTime,\n TimeUnit unit,\n BlockingQueue workQueue,\n ThreadFactory threadFactory) {\n this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,\n threadFactory, defaultHandler);\n }\n // 指定核心線程數，最大線程數，非核心線程沒有任務的存活時間，時間單位，任務隊列，拒絕任務處理器\n public ThreadPoolExecutor(int corePoolSize,\n int maximumPoolSize,\n long keepAliveTime,\n TimeUnit unit,\n BlockingQueue workQueue,\n RejectedExecutionHandler handler) {\n this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,\n Executors.defaultThreadFactory(), handler);\n }\n // 最後其實都是調用了這個方法\n public ThreadPoolExecutor(int corePoolSize,\n int maximumPoolSize,\n long keepAliveTime,\n TimeUnit unit,\n BlockingQueue workQueue,\n ThreadFactory threadFactory,\n RejectedExecutionHandler handler) {\n ...\n }\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"其實，除了顯示的指定上面的參數之外，JDK也封裝了一些直接創建線程池的方法給我們，那就是","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Executors","attrs":{}}],"attrs":{}},{"type":"text","text":":","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":" // 固定線程數量的線程池，無界的隊列\n public static ExecutorService newFixedThreadPool(int nThreads) {\n return new ThreadPoolExecutor(nThreads, nThreads,\n 0L, TimeUnit.MILLISECONDS,\n new LinkedBlockingQueue());\n }\n // 單個線程的線程池，無界的隊列，按照任務提交的順序，串行執行 \n public static ExecutorService newSingleThreadExecutor(ThreadFactory threadFactory) {\n return new FinalizableDelegatedExecutorService\n (new ThreadPoolExecutor(1, 1,\n 0L, TimeUnit.MILLISECONDS,\n new LinkedBlockingQueue(),\n threadFactory));\n }\n // 動態調節，沒有核心線程，全部都是普通線程，每個線程存活60s，使用容量爲1的阻塞隊列\n public static ExecutorService newCachedThreadPool() {\n return new ThreadPoolExecutor(0, Integer.MAX_VALUE,\n 60L, TimeUnit.SECONDS,\n new SynchronousQueue());\n }\n // 定時任務線程池\n public static ScheduledExecutorService newSingleThreadScheduledExecutor() {\n return new DelegatedScheduledExecutorService\n (new ScheduledThreadPoolExecutor(1));\n }\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"但是一般是不推薦使用上面別人封裝的線程池的哈！！！","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"線程池的底層參數以及核心方法","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"看完上面的創建參數大家可能會有點懵，但是沒關係，一一爲大家道來：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/eb/ebf5c72919a6fba8ad2e732040b7ef29.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以看出，當有任務進來的時候，先判斷核心線程池是不是已經滿了，如果還沒有，將會繼續創建線程。注意，如果一個任務進來，創建線程執行，執行完成，線程空閒下來，這時候再來一個任務，是會繼續使用之前的線程，還是重新創建一個線程來執行呢？","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"答案是重新創建線程，這樣線程池可以快速達到核心線程數的規模大小，以便快速響應後面的任務。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果線程數量已經到達核心線程數，來了任務，線程池的線程又都不是空閒狀態，那麼就會判斷隊列是不是滿的，倘若隊列還有空間，那麼就會把任務放進去隊列中，等待線程領取執行。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果任務隊列已經滿了，放不下任務，那麼就會判斷線程數是不是已經到最大線程數了，要是還沒有到達，就會繼續創建線程並執行任務，這個時候創建的是非核心部分線程。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果已經到達最大線程數，那麼就不能繼續創建線程了，只能執行拒絕策略，默認的拒絕策略是丟棄任務，我們可以自定義拒絕策略。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"值得注意的是，倘若之前任務比較多，創建出了一些非核心線程，那麼任務少了之後，領取不到任務，過了一定時間，非核心線程就會銷燬，只剩下核心線程池的數量的線程。這個時間就是前面說的","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"keepAliveTime","attrs":{}}],"attrs":{}},{"type":"text","text":"。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"提交任務","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"提交任務，我們看","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"execute()","attrs":{}}],"attrs":{}},{"type":"text","text":"，會先獲取線程池的狀態和個數，要是線程個數還沒達到核心線程數，會直接添加線程，否則會放到任務隊列，如果任務隊列放不下，會繼續增加線程，但是不是增加核心線程。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":" public void execute(Runnable command) {\n if (command == null)\n throw new NullPointerException();\n // 獲取狀態和個數\n int c = ctl.get();\n // 如果個數小於核心線程數\n if (workerCountOf(c) < corePoolSize) {\n // 直接添加\n if (addWorker(command, true))\n return;\n // 添加失敗則繼續獲取\n c = ctl.get();\n }\n // 判斷線程池狀態是不是運行中，任務放到隊列中\n if (isRunning(c) && workQueue.offer(command)) {\n // 再次檢查\n int recheck = ctl.get();\n // 判斷線程池是不是還在運行\n if (! isRunning(recheck) && remove(command))\n // 如果不是，那麼就拒絕並移除任務\n reject(command);\n else if (workerCountOf(recheck) == 0)\n // 如果線程數爲0，並且還在運行，那麼就直接添加\n addWorker(null, false);\n }else if (!addWorker(command, false))\n // 添加任務隊列失敗，拒絕\n reject(command);\n }\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"上面的源碼中，調用了一個重要的方法：","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"addWorker(Runnable firstTask, boolean core)","attrs":{}}],"attrs":{}},{"type":"text","text":",該方法主要是爲了增加工作的線程，我們來看看它是如何執行的：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":" private boolean addWorker(Runnable firstTask, boolean core) {\n // 回到當前位置重試\n retry:\n for (;;) {\n // 獲取狀態\n int c = ctl.get();\n int rs = runStateOf(c);\n\n // 大於SHUTDOWN說明線程池已經停止\n // ! (rs == SHUTDOWN && firstTask == null && ! workQueue.isEmpty()) 表示三個條件至少有一個不滿足\n // 不等於SHUTDOWN說明是大於shutdown\n // firstTask ！= null 任務不是空的\n // workQueue.isEmpty() 隊列是空的\n if (rs >= SHUTDOWN &&\n ! (rs == SHUTDOWN &&\n firstTask == null &&\n ! workQueue.isEmpty()))\n return false;\n\n for (;;) {\n // 工作線程數\n int wc = workerCountOf(c);\n // 是否符合容量\n if (wc >= CAPACITY ||\n wc >= (core ? corePoolSize : maximumPoolSize))\n return false;\n // 添加成功，跳出循環\n if (compareAndIncrementWorkerCount(c))\n break retry;\n c = ctl.get(); // Re-read ctl\n // cas失敗，重新嘗試\n if (runStateOf(c) != rs)\n continue retry;\n // else CAS failed due to workerCount change; retry inner loop\n }\n }\n\n // 前面線程計數增加成功\n boolean workerStarted = false;\n boolean workerAdded = false;\n Worker w = null;\n try {\n // 創建了一個worker，包裝了任務\n w = new Worker(firstTask);\n final Thread t = w.thread;\n // 線程創建成功\n if (t != null) {\n // 獲取鎖\n final ReentrantLock mainLock = this.mainLock;\n mainLock.lock();\n try {\n // 再次確認狀態\n int rs = runStateOf(ctl.get());\n if (rs < SHUTDOWN ||\n (rs == SHUTDOWN && firstTask == null)) {\n // 如果線程已經啓動，失敗\n if (t.isAlive()) // precheck that t is startable\n throw new IllegalThreadStateException();\n // 新增線程到集合\n workers.add(w);\n // 獲取大小\n int s = workers.size();\n // 判斷最大線程池數量\n if (s > largestPoolSize)\n largestPoolSize = s;\n // 已經添加工作線程\n workerAdded = true;\n }\n } finally {\n // 解鎖\n mainLock.unlock();\n }\n // 如果已經添加\n if (workerAdded) {\n // 啓動線程\n t.start();\n workerStarted = true;\n }\n }\n } finally {\n // 如果沒有啓動\n if (! workerStarted)\n // 失敗處理\n addWorkerFailed(w);\n }\n return workerStarted;\n }\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"處理任務","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"前面在介紹","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Worker","attrs":{}}],"attrs":{}},{"type":"text","text":"這個類的時候，我們講解到其實它的","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"run()","attrs":{}}],"attrs":{}},{"type":"text","text":"方法調用的是外部的","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"runWorker()","attrs":{}}],"attrs":{}},{"type":"text","text":"方法，那麼我們來看看","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"runWorkder()","attrs":{}}],"attrs":{}},{"type":"text","text":"方法：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"首先，它會直接處理自己的firstTask,這個任務並沒有在任務隊列裏面，而是它自己持有的：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"final void runWorker(Worker w) {\n // 當前線程\n Thread wt = Thread.currentThread();\n // 第一個任務\n Runnable task = w.firstTask;\n // 重置爲null\n w.firstTask = null;\n // 允許打斷\n w.unlock();\n boolean completedAbruptly = true;\n try {\n // 任務不爲空，或者獲取的任務不爲空\n while (task != null || (task = getTask()) != null) {\n // 加鎖\n w.lock();\n //如果線程池停止，確保線程被中斷;\n //如果不是，確保線程沒有被中斷。這\n //在第二種情況下需要複查處理\n // shutdown - now競賽同時清除中斷\n if ((runStateAtLeast(ctl.get(), STOP) ||\n (Thread.interrupted() &&\n runStateAtLeast(ctl.get(), STOP))) &&\n !wt.isInterrupted())\n wt.interrupt();\n try {\n // 執行之前回調方法（可以由我們自己實現）\n beforeExecute(wt, task);\n Throwable thrown = null;\n try {\n // 執行任務\n task.run();\n } catch (RuntimeException x) {\n thrown = x; throw x;\n } catch (Error x) {\n thrown = x; throw x;\n } catch (Throwable x) {\n thrown = x; throw new Error(x);\n } finally {\n // 執行之後回調方法\n afterExecute(task, thrown);\n }\n } finally {\n // 置爲null\n task = null;\n // 更新完成任務\n w.completedTasks++;\n w.unlock();\n }\n }\n // 完成\n completedAbruptly = false;\n } finally {\n // 處理線程退出相關工作\n processWorkerExit(w, completedAbruptly);\n }\n }\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"上面可以看到如果當前的任務是null，會去獲取一個task，我們看看","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"getTask()","attrs":{}}],"attrs":{}},{"type":"text","text":"，裏面涉及到了兩個參數，一個是是不是允許核心線程銷燬，另外一個是線程數是不是大於核心線程數，如果滿足條件，就從隊列中取出任務，如果超時取不到，那就返回空，表示沒有取到任務，沒有取到任務，就不會執行前面的循環，就會觸發線程銷燬","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"processWorkerExit()","attrs":{}}],"attrs":{}},{"type":"text","text":"等工作。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"private Runnable getTask() {\n // 是否超時\n boolean timedOut = false; // Did the last poll() time out?\n\n for (;;) {\n int c = ctl.get();\n int rs = runStateOf(c);\n\n // SHUTDOWN狀態繼續處理隊列中的任務，但是不接收新的任務\n if (rs >= SHUTDOWN && (rs >= STOP || workQueue.isEmpty())) {\n decrementWorkerCount();\n return null;\n }\n // 線程數\n int wc = workerCountOf(c);\n\n // 是否允許核心線程超時或者線程數大於核心線程數\n boolean timed = allowCoreThreadTimeOut || wc > corePoolSize;\n\n if ((wc > maximumPoolSize || (timed && timedOut))\n && (wc > 1 || workQueue.isEmpty())) {\n // 減少線程成功，就返回null，後面由processWorkerExit()處理\n if (compareAndDecrementWorkerCount(c))\n return null;\n continue;\n }\n\n try {\n // 如果允許核心線程關閉，或者超過了核心線程，就可以在超時的時間內獲取任務，或者直接取出任務\n Runnable r = timed ?\n workQueue.poll(keepAliveTime, TimeUnit.NANOSECONDS) :\n workQueue.take();\n // 如果能取到任務，那就肯定可以執行\n if (r != null)\n return r;\n // 否則就獲取不到任務，超時了\n timedOut = true;\n } catch (InterruptedException retry) {\n timedOut = false;\n }\n }\n}\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"銷燬線程","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"前面提到，如果線程當前任務爲空，又允許核心線程銷燬，或者線程超過了核心線程數，等待了一定時間，超時了卻沒有從任務隊列獲取到任務的話，就會跳出循環執行到後面的線程銷燬（結束）程序。那銷燬線程的時候怎麼做呢？","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":" private void processWorkerExit(Worker w, boolean completedAbruptly) {\n // 如果是突然結束的線程，那麼之前的線程數是沒有調整的，這裏需要調整\n if (completedAbruptly)\n decrementWorkerCount();\n // 獲取鎖\n final ReentrantLock mainLock = this.mainLock;\n mainLock.lock();\n \n try {\n // 完成的任務數\n completedTaskCount += w.completedTasks;\n // 移除線程\n workers.remove(w);\n } finally {\n // 解鎖\n mainLock.unlock();\n }\n // 試圖停止\n tryTerminate();\n // 獲取狀態\n int c = ctl.get();\n // 比stop小，至少是shutdown\n if (runStateLessThan(c, STOP)) {\n // 如果不是突然完成\n if (!completedAbruptly) {\n // 最小值要麼是0，要麼是核心線程數，要是允許核心線程超時銷燬，那麼就是0\n int min = allowCoreThreadTimeOut ? 0 : corePoolSize;\n // 如果最小的是0或者隊列不是空的，那麼保留一個線程\n if (min == 0 && ! workQueue.isEmpty())\n min = 1;\n // 只要大於等於最小的線程數，就結束當前線程\n if (workerCountOf(c) >= min)\n return; // replacement not needed\n }\n // 否則的話，可能還需要新增工作線程\n addWorker(null, false);\n }\n }\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"如何停止線程池","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"停止線程池可以使用","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"shutdown()","attrs":{}}],"attrs":{}},{"type":"text","text":"或者","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"shutdownNow()","attrs":{}}],"attrs":{}},{"type":"text","text":"，","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"shutdown()","attrs":{}}],"attrs":{}},{"type":"text","text":"可以繼續處理隊列中的任務，而","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"shutdownNow()","attrs":{}}],"attrs":{}},{"type":"text","text":"會立即清理任務，並返回未執行的任務。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":" public void shutdown() {\n // 獲取鎖\n final ReentrantLock mainLock = this.mainLock;\n mainLock.lock();\n try {\n // 檢查停止權限\n checkShutdownAccess();\n // 更新狀態\n advanceRunState(SHUTDOWN);\n // 中斷所有線程\n interruptIdleWorkers();\n // 回調鉤子\n onShutdown(); // hook for ScheduledThreadPoolExecutor\n } finally {\n mainLock.unlock();\n }\n tryTerminate();\n }\n // 立刻停止\n public List shutdownNow() {\n List tasks;\n // 獲取鎖\n final ReentrantLock mainLock = this.mainLock;\n mainLock.lock();\n try {\n // 檢查停止權限\n checkShutdownAccess();\n // 更新狀態到stop\n advanceRunState(STOP);\n // 中斷所有線程\n interruptWorkers();\n // 清理隊列\n tasks = drainQueue();\n } finally {\n mainLock.unlock();\n }\n tryTerminate();\n // 返回任務列表（未完成）\n return tasks;\n }\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"execute()和submit()方法","attrs":{}}]},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"execute() ","attrs":{}}],"attrs":{}},{"type":"text","text":"方法可以提交不需要返回值的任務，無法判斷任務是否被線程池執行是否成功","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"submit()","attrs":{}}],"attrs":{}},{"type":"text","text":"方法用於提交需要返回值的任務。線程池會返回一個future類型的對象，通過這個對象，我們調用","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"get()","attrs":{}}],"attrs":{}},{"type":"text","text":"方法就可以","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"阻塞","attrs":{}},{"type":"text","text":"，直到獲取到線程執行完成的結果，同時我們也可以使用有超時時間的等待方法","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"get（long timeout，TimeUnit unit）","attrs":{}}],"attrs":{}},{"type":"text","text":",這樣不管線程有沒有執行完成，如果到時間，也不會阻塞，直接返回null。返回的是","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"RunnableFuture","attrs":{}}],"attrs":{}},{"type":"text","text":"對象，繼承了","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Runnable, Future","attrs":{}}],"attrs":{}},{"type":"text","text":"兩個接口：","attrs":{}}]}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"public interface RunnableFuture extends Runnable, Future {\n /**\n * Sets this Future to the result of its computation\n * unless it has been cancelled.\n */\n void 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，這是我們可以參考的思路。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"線程池隔離","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"線程隔離，很多同學可能知道，就是不同的任務放在不同的線程裏面運行，而線程池隔離，一般是按照業務類型來隔離，比如訂單的處理線程放在一個線程池，會員相關的處理放在一個線程池。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"也可以通過核心和非核心來隔離，核心處理流程放在一起，非核心放在一起，兩個使用不一樣的參數，不一樣的拒絕策略，儘量保證多個線程池之間不影響，並且最大可能保住核心線程的運行，非核心線程可以忍受失敗。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"Hystrix","attrs":{}}],"attrs":{}},{"type":"text","text":"裏面運用到這個技術，","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Hystrix","attrs":{}}],"attrs":{}},{"type":"text","text":"的線程隔離技術，來防止不同的網絡請求之間的雪崩，即使依賴的一個服務的線程池滿了，也不會影響到應用程序的其他部分。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"關於作者","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"秦懷，公衆號【","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"秦懷雜貨店","attrs":{}},{"type":"text","text":"】作者，技術之路不在一時，山高水長，縱使緩慢，馳而不息。個人寫作方向：Java源碼解析，JDBC，Mybatis，Spring，redis，分佈式，劍指Offer，LeetCode等，認真寫好每一篇文章，不喜歡標題黨，不喜歡花裏胡哨，大多寫系列文章，不能保證我寫的都完全正確，但是我保證所寫的均經過實踐或者查找資料。遺漏或者錯誤之處，還望指正。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"http://aphysia.cn/archives/2020","title":"","type":null},"content":[{"type":"text","text":"2020年我寫了什麼？","attrs":{}}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"https://damaer.github.io/Coding/#/","title":"","type":null},"content":[{"type":"text","text":"開源編程筆記","attrs":{}}]}]}]}