锁定从Singleton EJB到无状态会话Bean的传播(Lock propagation from Singleton EJB to Stateless Session Bean)

 我有这个EJB Singleton（EJB 3.1）： 
 
@Singleton
@Startup
@Lock(LockType.READ)
public class SingletonExample {

@EJB
private StatelessSBExample stlsb;
...
    @Schedule(..........., persistent = false)
    @AccessTimeout(0)
    @Lock(LockType.READ)
    public void call1SB() {
         stlsb.doSomething();
    }

    @Schedule(..........., persistent = false)
    @AccessTimeout(0)
    @Lock(LockType.READ)
    public void call2SB() {
        stlsb.doSomething();
    }
}
 
 我的bean是一个传统的EJB无状态会话Bean： 
 
@Stateless
public class StatelessSBExample {
    public void domSomething() {
    ...
    }
}
 
 用visualvm监控，我意识到一些线程正在积累。 该应用程序以Thread Live Peak = 92开始，现在为102，并且正在增加。 在VisualVM线程中，我有几个状态为“Park”和“Wait”的线程。 在我的线程转储中，我有很多： 
 
"Thread-42" - Thread t@190
   java.lang.Thread.State: WAITING
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for <71bfce05> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
    - None
 
 和 
 
"__ejb-thread-pool13" - Thread t@130
   java.lang.Thread.State: WAITING
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for <5cfe398e> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
    - None
 
 我的错在哪里？ 我只想执行call1SB（），如果它正在运行，不会再次执行此方法（与call2SB相同） 
 
 PS我不能使用LockType.WRITE，因为我想同时执行call1SB（）和call2SB（）（我没有属性在我的Singleton ..只有方法） 

I have this EJB Singleton (EJB 3.1):
 
@Singleton
@Startup
@Lock(LockType.READ)
public class SingletonExample {

@EJB
private StatelessSBExample stlsb;
...
    @Schedule(..........., persistent = false)
    @AccessTimeout(0)
    @Lock(LockType.READ)
    public void call1SB() {
         stlsb.doSomething();
    }

    @Schedule(..........., persistent = false)
    @AccessTimeout(0)
    @Lock(LockType.READ)
    public void call2SB() {
        stlsb.doSomething();
    }
}
 
My bean is a tradicional EJB Stateless Session Bean:
 
@Stateless
public class StatelessSBExample {
    public void domSomething() {
    ...
    }
}
 
Monitoring with visualvm, I realized that some threads are accumulating. The application started with Thread Live Peak = 92 and is now 102. And it is increasing. In VisualVM Threads, I have several threads with the status "Park" and "Wait". In my Thread Dump I have a lot:
 
"Thread-42" - Thread t@190
   java.lang.Thread.State: WAITING
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for <71bfce05> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
    - None
 
and 
 
"__ejb-thread-pool13" - Thread t@130
   java.lang.Thread.State: WAITING
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for <5cfe398e> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
    - None
 
Where is my fault? I just want to execute call1SB() and, if it is running, doesnt execute this method again (the same to call2SB)
 
P.S. I can not use LockType.WRITE because I want to execute call1SB() and call2SB() at the same time (I dont have attributes in my Singleton.. only methods)

原文：https://stackoverflow.com/questions/40872709