update comment

019caoyu · 019caoyu · commit e2afc50d10e7 · 2021-02-02T22:15:31.000+08:00
diff --git a/03concurrency/0301/src/main/java/java0/conc0301/op/Join.java b/03concurrency/0301/src/main/java/java0/conc0301/op/Join.java
@@ -1,12 +1,15 @@
 package java0.conc0301.op;
 
+/**
+ * 总结：线程A结束的时候，JVM内部会发送通知 notifyAll 给该线程对象A上的等待线程，唤醒在线程对象A上等待的线程
+ */
 public class Join {
     
     public static void main(String[] args) {
         Object oo = new Object();
     
         MyThread thread1 = new MyThread("thread1 -- ");
-        //oo = thread1;
+        oo = thread1;
         thread1.setOo(oo);
         thread1.start();
         
@@ -42,10 +45,12 @@ public MyThread(String name) {
     
     @Override
     public void run() {
-        synchronized (oo) { // 这里用oo或this，效果不同
+        synchronized (this) { // 这里用oo或this，效果不同
             for (int i = 0; i < 100; i++) {
                 System.out.println(name + i);
             }
+            //my Test: add notifyAll to solve dead lock
+            //oo.notifyAll();
         }
     }
     
diff --git a/03concurrency/0301/src/main/java/java0/conc0301/op/WaitAndNotify.java b/03concurrency/0301/src/main/java/java0/conc0301/op/WaitAndNotify.java
@@ -37,7 +37,10 @@ public static void main(String[] args) {
 class MethodClass {
     // 定义生产最大量
     private final int MAX_COUNT = 20;
-    
+
+    /**
+     * 单线程创建 product, 不需要加锁
+     */
     int productCount = 0;
     
     public synchronized void product() throws InterruptedException {
diff --git a/03concurrency/0301/src/main/java/java0/conc0301/sync/Counter.java b/03concurrency/0301/src/main/java/java0/conc0301/sync/Counter.java
@@ -1,5 +1,8 @@
 package java0.conc0301.sync;
 
+/**
+ * volatile 只能保证有序性和可见性，不能保证原子性
+ */
 public class Counter {
     
     public final static int A=10;
diff --git a/03concurrency/0301/src/main/java/java0/conc0301/sync/Thread1.java b/03concurrency/0301/src/main/java/java0/conc0301/sync/Thread1.java
@@ -1,11 +1,19 @@
 
 package java0.conc0301.sync;
 
+
+/**
+ * Thread 线程对象中的任意方法获取的 this 代表线程对象本身，并不代表线程信息（线程信息中包括操作系统线程）
+ * Thread.currentThread() 代表操作系统对应的线程信息.
+ * 所以 this ！= Thread.currentThread() ,this 代表 Task 对象信息
+ * 如下所示：TA 线程和 TB线程在操作系统上创建了两个线程对应 A线程 和 B线程，但是它们公用一个Task 对象信息， this是 task 对象信息
+ */
 public class Thread1 implements Runnable {
 
     @Override
     public void run() {
         synchronized (this) {
+            System.out.println(this);
             for (int i = 0; i < 10; i++) {
                 System.out.println(Thread.currentThread().getName() + " synchronized loop " + i);
             }
@@ -14,8 +22,10 @@ public void run() {
 
     public static void main(String[] args) {
         Thread1 t1 = new Thread1();
+        System.out.println("the Thread1 obj t1:" + t1);
         Thread ta = new Thread(t1, "A");
         Thread tb = new Thread(t1, "B");
+
         ta.start();
         tb.start();
     }
