InheritableThreadLocalDemo

src/test/java/com/laker/admin/framework/ext/thread/InheritableThreadLocalDemo2.java

@@ -0,0 +1,113 @@
+package com.laker.admin.framework.ext.thread;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * <pre>
+ * 示例来着：https://blog.csdn.net/qq_40378034/article/details/115272581
+ * 因为可继承threadlocal，是在创建子线程时将父线程中的本地变量值复制到子线程，
+ *  - 即复制的时机为创建子线程时.
+ * 但是当和线程池配合时，线程池有多场景不会创建新线程，而是复用，所以这个例子导致线程本地变量混乱
+ * 解决方案
+ *  - 1. 使用阿里的TransmittableThreadLocal
+ *  - 2. 自己手动从父线程复制到子线程，参考 MDC线程池复制。
+ *  结果：
+ *  pool-1-thread-3:2
+ * pool-1-thread-4:3
+ * pool-1-thread-1:0
+ * pool-1-thread-7:6
+ * pool-1-thread-8:7
+ * pool-1-thread-5:4
+ * pool-1-thread-6:5
+ * pool-1-thread-9:8
+ * pool-1-thread-10:9
+ * pool-1-thread-2:1
+ * ------------这里 线程pool-2-thread-5 复用了，所以都是5
+ * parentThreadName:pool-1-thread-6:5  pool-2-thread-5
+ * parentThreadName:pool-1-thread-5:5  pool-2-thread-5
+ * parentThreadName:pool-1-thread-8:5  pool-2-thread-5
+ * parentThreadName:pool-1-thread-3:5  pool-2-thread-5
+ * parentThreadName:pool-1-thread-7:5  pool-2-thread-5
+ * ------------这里
+ * parentThreadName:pool-1-thread-10:9  pool-2-thread-1
+ * parentThreadName:pool-1-thread-1:5  pool-2-thread-5
+ * parentThreadName:pool-1-thread-4:3  pool-2-thread-2
+ * parentThreadName:pool-1-thread-2:1  pool-2-thread-3
+ * parentThreadName:pool-1-thread-9:8  pool-2-thread-4
+ * </pre>
+ */
+public class InheritableThreadLocalDemo2 {
+    /**
+     * 模拟tomcat线程池
+     */
+    private static ExecutorService tomcatExecutors = Executors.newFixedThreadPool(10);
+
+    /**
+     * 业务线程池,默认Control中异步任务执行线程池
+     */
+    private static ExecutorService businessExecutors = Executors.newFixedThreadPool(5);
+
+    /**
+     * 线程上下文环境,模拟在Control这一层,设置环境变量,然后在这里提交一个异步任务,模拟在子线程中,是否可以访问到刚设置的环境变量值
+     */
+    private static ThreadLocal<Integer> requestIdThreadLocal = new InheritableThreadLocal<>();
+
+    /**
+     * 模式10个请求,每个请求执行ControlThread的逻辑,其具体实现就是,先输出父线程的名称,
+     * 然后设置本地环境变量,并将父线程名称传入到子线程中,在子线程中尝试获取在父线程中的设置的环境变量
+     *
+     * @param args
+     * @throws InterruptedException
+     */
+    public static void main(String[] args) throws InterruptedException {
+        for (int i = 0; i < 10; ++i) {
+            tomcatExecutors.submit(new ControlThread(i));
+        }
+
+        TimeUnit.SECONDS.sleep(10);
+        businessExecutors.shutdown();
+        tomcatExecutors.shutdown();
+    }
+
+    /**
+     * 模拟Control任务
+     */
+    static class ControlThread implements Runnable {
+        private int i;
+
+        public ControlThread(int i) {
+            this.i = i;
+        }
+
+        @Override
+        public void run() {
+            System.out.println(Thread.currentThread().getName() + ":" + i);
+            requestIdThreadLocal.set(i);
+            //使用线程池异步处理任务
+            businessExecutors.submit(new BusinessTask(Thread.currentThread().getName()));
+            requestIdThreadLocal.remove();
+
+        }
+    }
+
+    /**
+     * 业务任务,主要是模拟在Control控制层,提交任务到线程池执行
+     */
+    static class BusinessTask implements Runnable {
+        private String parentThreadName;
+        private int i;
+        public BusinessTask(String parentThreadName) {
+            this.parentThreadName = parentThreadName;
+             i = requestIdThreadLocal.get();
+        }
+
+        @Override
+        public void run() {
+            //如果与上面的能对应上来,则说明正确,否则失败
+            System.out.println("parentThreadName:" + parentThreadName + ":" + i + "  " + Thread.currentThread().getName());
+            requestIdThreadLocal.remove();
+        }
+    }
+}