ajax 调用后台异步代码问题！

Thread t = new Thread(){
     public void run(){
Log.info("*********** 测试2 ***********", "");
     }
}.start();
t.join();  //等待

@shnulaa：Thread t = new Thread(){
     public void run(){
Log.info("*********** 测试2 ***********", "");
     }
}.start();
t.join();  //等待这种写法编译不通过！

@shnulaa：能不能解释一下，谢谢

ajax没有返回是什么意思？
是指没有callback吗？只打印了“测试1”
-> 测试2没有打印是可以理解的，
但是测试3没有打印是不正常的，除非之前出了异常，即使在thread中出异常也不会导致测试3没有打印。t.join();
-> 加上的原因是等待该线程完成后，继续。想确认
1 到底想什么时候返回ajax回调函数？测试3打印完还是另外线程方法结束后。
2 因为业务不知道，为什么要异步？要实现什么功能？

@shnulaa：逻辑是这样的：页面使用ajax调用后台，后台会返回页面一个参数，页面判断这个参数进行提示用。
现在出现新需求，后台除了返回那个参数外，另外还要做一系列其他的处理。但是这些处理跟用户无关，所以为了不影响正常给用户提示，我将新增加的一系列操作放在了一个新的线程里，不影响给用户正常提示。想要的结果是：ajax 请求过来后，新线程中的操作不影响主线程给前台返回参数，并做提示用。也就是一个线程用来ajax前台页面提示，另外一个线程用来其他事情的操作。刚才测试发现，“测试3”打印出来。想在“测试3”打印完后就返回ajax回调，另外线程继续处理。不知道说明白了没，多谢关注！

那也没什么问题，request线程打印了测试3以后，回归线程池，任务结束，而新建的线程
也会异步的继续执行，如果该线程为非守护线程，他的生命周期就是run方法
逻辑的结束。新建的线程不会随着request线程的结束而结束。
就会有一个问题，就是页面上显示已经完成，但是其实还有一部分的功能还没有实现。最好在新建的线程结束有一个回调。

唉~ 郁闷的是本地无法调试只能打log放服务器上去试本地单元测试模拟直接调用一切正常，放服务器上用ajax调就是不走

Log.info("*********** 测试1 ***********", "");

new Thread(){
   public void run(){
Log.info("*********** 测试2 ***********", "");
return;
   }
}.start();

Log.info("*********** 测试3 ***********", "");输出：
*********** 测试1 ***********
回调失败Log.info("*********** 测试1 ***********", "");

//new Thread(){
//   public void run(){
// Log.info("*********** 测试2 ***********", "");
// return;
//   }
//}.start();

Log.info("*********** 测试3 ***********", "");输出：
*********** 测试1 ***********
*********** 测试3 ***********
回调正常

现在可以确定，不是ajax的原因

new Thread(){
   public void run(){
    Log.info("*********** 测试2 ***********", "");
    return;
   }
}.start();肯定阻塞了。试试下面的 Thread t1 = new Thread(new Runnable() {
@Override
public void run() {
System.out.println("*********** 测试2 ***********");
}
});
t1.start();
1 Runnable
2 Log.info -> System.out.println

两个地方都改了
1 Runnable
2 Log.info -> System.out.println还是不行，到 new Thread 就停了！

什么容器？环境 linux, windows?
框架？

环境是linux
页面发布在resin下
java代码没有容器，直接启动jar
没有用框架，java+jsp

不过整个环境依赖一个平台，主要做参数存储用。这个平台底层是用ThreadLocal实现的

jstack -l [pid] > threadLog看一下执行好以后，threadLog 发来看下。

>jstack -l [pid] > threadLog
Attaching to remote server [pid], please wait...
Error attaching to remote server: java.net.MalformedURLException: invalid URL String: //[pid]/SARemoteDebugger
报错了。

$.../201402/28> jstack -l pid > threadLog
Attaching to remote server pid, please wait...
Error attaching to remote server: java.rmi.ConnectException: Connection refused to host: pid; nested exception is:
java.net.ConnectException: Connection timed out
超时

不知道这些是否有价值："file" daemon prio=10 tid=0x80eca800 nid=0x9ca in Object.wait() [0x80dfe000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x94173228> (a org.apache.hadoop.metrics2.impl.SinkQueue)
at java.lang.Object.wait(Object.java:485)
at org.apache.hadoop.metrics2.impl.SinkQueue.waitForData(SinkQueue.java:109)
- locked <0x94173228> (a org.apache.hadoop.metrics2.impl.SinkQueue)
at org.apache.hadoop.metrics2.impl.SinkQueue.consumeAll(SinkQueue.java:78)
at org.apache.hadoop.metrics2.impl.MetricsSinkAdapter.publishMetricsFromQueue(MetricsSinkAdapter.java:113)
at org.apache.hadoop.metrics2.impl.MetricsSinkAdapter$2.run(MetricsSinkAdapter.java:89)   Locked ownable synchronizers:
- None"pool-3-thread-2" prio=10 tid=0x80e85800 nid=0x9c9 waiting on condition [0x80ffe000]
   java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for  <0x94171418> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:196)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2025)
at java.util.concurrent.DelayQueue.take(DelayQueue.java:164)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:609)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:602)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:947)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:662)   Locked ownable synchronizers:
- None"New I/O server boss #1 (channelId: 2737550, /192.168.0.143:60000)" prio=10 tid=0x81977000 nid=0x9c8 runnable [0x817ad000]
   java.lang.Thread.State: RUNNABLE
at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:210)
at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
- locked <0x941733b0> (a sun.nio.ch.Util$2)
- locked <0x941733c0> (a java.util.Collections$UnmodifiableSet)
- locked <0x94173370> (a sun.nio.ch.EPollSelectorImpl)
at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
at org.jboss.netty.channel.socket.nio.NioServerSocketPipelineSink$Boss.run(NioServerSocketPipelineSink.java:241)
at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
at org.jboss.netty.util.internal.IoWorkerRunnable.run(IoWorkerRunnable.java:46)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)   Locked ownable synchronizers:
- <0x94173468> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
- <0x941cef68> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)"pool-3-thread-1" prio=10 tid=0x81989000 nid=0x9c7 waiting on condition [0x817fe000]
   java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for  <0x94171418> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:196)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2025)
at java.util.concurrent.DelayQueue.take(DelayQueue.java:164)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:609)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:602)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:947)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:662)   Locked ownable synchronizers:
- None"Low Memory Detector" daemon prio=10 tid=0x8319a000 nid=0x9c5 runnable [0x00000000]
   java.lang.Thread.State: RUNNABLE   Locked ownable synchronizers:
- None"C2 CompilerThread1" daemon prio=10 tid=0x83198000 nid=0x9c4 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE   Locked ownable synchronizers:
- None"C2 CompilerThread0" daemon prio=10 tid=0x83196000 nid=0x9c3 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE   Locked ownable synchronizers:
- None"Signal Dispatcher" daemon prio=10 tid=0x83194800 nid=0x9c2 runnable [0x00000000]
   java.lang.Thread.State: RUNNABLE   Locked ownable synchronizers:
- None"Finalizer" daemon prio=10 tid=0x83186400 nid=0x9c1 in Object.wait() [0x830fe000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x94176150> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:118)
- locked <0x94176150> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:134)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159)   Locked ownable synchronizers:
- None"Reference Handler" daemon prio=10 tid=0x83184c00 nid=0x9c0 in Object.wait() [0x83267000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x94176300> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:485)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116)
- locked <0x94176300> (a java.lang.ref.Reference$Lock)   Locked ownable synchronizers:
- None"VM Thread" prio=10 tid=0x83181000 nid=0x9bf runnable "GC task thread#0 (ParallelGC)" prio=10 tid=0x09e5d400 nid=0x9ad runnable "GC task thread#1 (ParallelGC)" prio=10 tid=0x09e5ec00 nid=0x9ae runnable "GC task thread#2 (ParallelGC)" prio=10 tid=0x09e60000 nid=0x9af runnable "GC task thread#3 (ParallelGC)" prio=10 tid=0x09e61800 nid=0x9b0 runnable "GC task thread#4 (ParallelGC)" prio=10 tid=0x09e62c00 nid=0x9b1 runnable "GC task thread#5 (ParallelGC)" prio=10 tid=0x09e64400 nid=0x9b2 runnable "GC task thread#6 (ParallelGC)" prio=10 tid=0x09e65c00 nid=0x9b3 runnable "GC task thread#7 (ParallelGC)" prio=10 tid=0x09e67000 nid=0x9b4 runnable "GC task thread#8 (ParallelGC)" prio=10 tid=0x09e68800 nid=0x9b5 runnable "GC task thread#9 (ParallelGC)" prio=10 tid=0x09e69c00 nid=0x9b6 runnable "GC task thread#10 (ParallelGC)" prio=10 tid=0x09e6b400 nid=0x9b7 runnable "GC task thread#11 (ParallelGC)" prio=10 tid=0x09e6c800 nid=0x9b8 runnable "GC task thread#12 (ParallelGC)" prio=10 tid=0x09e6e000 nid=0x9b9 runnable "GC task thread#13 (ParallelGC)" prio=10 tid=0x09e6f800 nid=0x9ba runnable "GC task thread#14 (ParallelGC)" prio=10 tid=0x09e70c00 nid=0x9bb runnable "GC task thread#15 (ParallelGC)" prio=10 tid=0x09e72400 nid=0x9bc runnable "GC task thread#16 (ParallelGC)" prio=10 tid=0x09e73800 nid=0x9bd runnable "GC task thread#17 (ParallelGC)" prio=10 tid=0x09e75000 nid=0x9be runnable "VM Periodic Task Thread" prio=10 tid=0x8319c000 nid=0x9c6 waiting on condition JNI global references: 1221

把创建的线程id和名字打印出来看一下。
        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("*********** 测试2 ***********");
            }
        });
        System.out.println("the created thread id: " + t1.getId() + ", thread Name:" + t1.getName());
        t1.start();

发现问题
代码还没有执行到：
System.out.println("the created thread id: " + t1.getId() + ", thread Name:" + t1.getName());
这里，就已经停顿了。
也就是说，t1.start()没有被执行也！

实在不太懂jstack这个东西怎么使用，上周我发给你的那个log是输出threadlog最后的信息，上面还有很多，怎么看是否全

问题已经解决，代码没有问题，是所在平台的问题。非常感谢，@shnulaa 对问题的持续关注，也很大程度的帮助了我，好人一生平安，哈哈

调试易

ajax 调用后台异步代码问题！

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