我们正在使用Wildfly 10.1.0 Final。
我们遇到了由线程不断增长引起的OutOfMemoryError。
检查线程转储后。
我们发现有数千个Remoting“端点”任务-N线程。
什么是Remoting“端点”任务-N线程？
它们是由jboss-remoting创建的吗？
重新启动服务器后，我们发现在开始时，它们只有16个线程：
远程“端点”任务-1~远程“端点”任务-16。
服务器运行几天或几个月后，可能会有数百或数千个Remoting线程：
下面列出了一个线程转储片段。
在这个线程转储中，有几个“Remoting”端点“task-11”具有不同的编号。
其他任务也是如此，例如task-1到task-16。
除了等待之外，所有这些线程都无所事事
"Remoting "endpoint" task-11" #55415 daemon prio=5 os_prio=0 tid=0x00007f2b8c0a8000 nid=0x276e waiting on condition [0x00007f280a36c000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabee2b8> (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:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-11" #55417 daemon prio=5 os_prio=0 tid=0x00007f2ba003f800 nid=0x276d waiting on condition [0x00007f2794818000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabecf40> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-11" #55414 daemon prio=5 os_prio=0 tid=0x00007f2b98023800 nid=0x276b waiting on condition [0x00007f2792bfc000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabeda50> (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:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-10" #55411 daemon prio=5 os_prio=0 tid=0x00007f2ba003e000 nid=0x276a waiting on condition [0x00007f27926f7000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabecf40> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-10" #55413 daemon prio=5 os_prio=0 tid=0x00007f2b8c0a7000 nid=0x2769 waiting on condition [0x00007f27927f8000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabee2b8> (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:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-10" #55412 daemon prio=5 os_prio=0 tid=0x00007f2b98022800 nid=0x2768 waiting on condition [0x00007f27c4815000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabeda50> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-9" #55372 daemon prio=5 os_prio=0 tid=0x00007f2c7408f000 nid=0x41df waiting on condition [0x00007f27907d8000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabece88> (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:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-8" #55369 daemon prio=5 os_prio=0 tid=0x00007f2c7408d000 nid=0x41dd waiting on condition [0x00007f27909da000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabece88> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-7" #55368 daemon prio=5 os_prio=0 tid=0x00007f2c7408b000 nid=0x41dc waiting on condition [0x00007f2790adb000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabece88> (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:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-6" #55367 daemon prio=5 os_prio=0 tid=0x00007f2c74089000 nid=0x41db waiting on condition [0x00007f2790bdc000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabece88> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-5" #55366 daemon prio=5 os_prio=0 tid=0x00007f2c74087000 nid=0x41da waiting on condition [0x00007f2790cdd000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabece88> (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:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-4" #55365 daemon prio=5 os_prio=0 tid=0x00007f2c74085000 nid=0x41d9 waiting on condition [0x00007f2790dde000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabece88> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-9" #55364 daemon prio=5 os_prio=0 tid=0x00007f2bd813c000 nid=0x41d8 waiting on condition [0x00007f2790edf000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabed500> (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:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Remoting "endpoint" task-9" #55363 daemon prio=5 os_prio=0 tid=0x00007f2bf4044000 nid=0x41d7 waiting on condition [0x00007f2790fe0000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006eabee3c0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
....
20180903
我发现“Remoting”端点“任务”线程是由“xnio”创建的。我发现xnio存在一个与我们的场景非常相似的问题：
https://issues.jboss.org/browse/XNIO-285
它说这个问题已在“xnio 3.6.0.Beta1”中修复。不幸的是，Wildfly 10.1.0正在使用xnio 3.4.0。当我尝试升级到xnio 3.6.5时，我得到了org / wildfly / common / context / Contextual的java.lang.NoClassDefFoundError。在升级包含“org / wildfly / common / context / Contextual”类的wildfly-common-1.4.0.Final.jar之后，NoClassDefFoundError仍然存在。
有没有其他方法可以防止Remoting“端点”任务线程增长？
您可能正在使用scoped EJB上下文进行远程方法执行。
每个作用域的EJB上下文都会创建新的线程，只是调用context.close()方法不会关闭上下文所以你得到OutOfMemoryError
如何关闭作用域的EJB客户端上下文？
答案是一样的，在EJB客户端上下文中使用close（）方法。但真正的问题是如何获得与JNDI上下文关联的相关范围EJB客户端上下文。在我们开始之前，了解用于EJB查找的ejb：JNDI命名空间以及JNDI上下文（通常是您在客户端代码中看到的InitialContext）如何相关是很重要的。 Java语言提供的JNDI API允许在JNDI框架中注册“URL上下文工厂”（有关详细信息，请参阅此处http://docs.oracle.com/javase/jndi/tutorial/provider/url/factory.html）。与该文档一样，URL上下文工厂可用于在JNDI查找期间解析URL字符串。当你进行远程EJB查找时，这就是ejb：前缀。 ejb：URL字符串由URL上下文工厂支持。
在内部，当对ejb：URL字符串进行查找时，会为该ejb：lookup创建相关的javax.naming.Context。让我们看一些代码以便更好地理解：
// JNDI context "A"
Context jndiCtx = new InitialContext(props);
// Now let's lookup a EJB
MyBean bean = jndiCtx.lookup("ejb:app/module/distinct/bean!interface");
因此，我们首先创建一个JNDI上下文，然后使用它来查找EJB。但是，使用ejb：JNDI名称进行bean查找只是一个语句，涉及到更多内容。查找该字符串时实际发生的是为ejb：URL字符串创建单独的javax.naming.Context。然后使用这个新的javax.naming.Context来查找该JNDI名称中的其余字符串。
让我们将这一行分解为多个语句以便更好地理解：
// Remember, the ejb: is backed by a URL context factory which returns a Context for the ejb: URL (that's why it's called a context factory)
final Context ejbNamingContext = (Context) jndiCtx.lookup("ejb:");
// Use the returned EJB naming context to lookup the rest of the JNDI string for EJB
final MyBean bean = ejbNamingContext.lookup("app/module/distinct/bean!interface");
如上所述，我们将该单个语句拆分为几个语句，以便更好地解释详细信息。因此，您可以看到在JNDI名称中解析ejb：URL字符串时，它将获取javax.naming.Context实例。此实例与用于执行查找的实例（在此示例中为jndiCtx）不同。这是一个需要理解的重要细节（由后面解释的原因）。现在，这个返回的实例用于查找JNDI字符串的其余部分（“app / module / distinct / bean！interface”），然后返回EJB代理。无论查询是在单个语句中还是在多个部分中完成，代码都是相同的。即为ejb：URL字符串创建javax.naming.Context的实例。
那么为什么我在标题为“如何关闭范围的EJB客户端上下文”一节中解释所有这些？原因是因为处理与JNDI上下文关联的作用域EJB客户端上下文的客户端应用程序会期望以下代码关闭关联的EJB客户端上下文，但是它会惊讶于它不会：
final Properties props = new Properties();
// mark it for scoped EJB client context
props.put("org.jboss.ejb.client.scoped.context","true");
// add other properties
props.put(....);
...
Context jndiCtx = new InitialContext(props);
try {
final MyBean bean = jndiCtx.lookup("ejb:app/module/distinct/bean!interface");
bean.doSomething();
} finally {
jndiCtx.close();
}
应用程序期望对jndiCtx.close（）的调用将有效地关闭与JNDI上下文关联的EJB客户端上下文。这不会发生，因为如前所述，支持ejb：URL字符串的javax.naming.Context是一个与代码关闭的实例不同的实例。 Java中的JNDI实现只关闭了调用close的上下文。因此，支持ejb：URL字符串的其他javax.naming.Context仍未关闭，这实际上意味着范围内的EJB客户端上下文也未关闭，这最终意味着与服务器的连接EJB客户端上下文也不会关闭。
现在让我们看看如何正确完成这项工作。我们知道ejb：URL字符串查找返回一个javax.naming.Context。我们所要做的就是保持对这个实例的引用，并在完成EJB调用时关闭它。所以这是它的样子：
final Properties props = new Properties();
// mark it for scoped EJB client context
props.put("org.jboss.ejb.client.scoped.context","true");
// add other properties
props.put(....);
...
Context jndiCtx = new InitialContext(props);
Context ejbRootNamingContext = (Context) jndiCtx.lookup("ejb:");
try {
final MyBean bean = ejbRootNamingContext.lookup("app/module/distinct/bean!interface"); // the rest of the EJB jndi string
bean.doSomething();
} finally {
try {
// close the EJB naming JNDI context
ejbRootNamingContext.close();
} catch (Throwable t) {
// log and ignore
}
try {
// also close our other JNDI context since we are done with it too
jndiCtx.close();
} catch (Throwable t) {
// log and ignore
}
}
如您所见，我们更改了代码，首先只对“ejb：”字符串进行查找以获取EJB命名上下文，然后使用该ejbRootNamingContext实例查找EJB JNDI名称的其余部分以获取EJB代理。然后，当关闭上下文时，我们关闭了ejbRootNamingContext（以及其他JNDI上下文）。关闭ejbRootNamingContext可确保关闭与该JNDI上下文关联的作用域EJB客户端上下文。实际上，这会关闭该EJB客户端上下文中与服务器的连接。
有关详细信息，请参阅 Scoped EJB client contexts
我发现Remoting“端点”任务线程是由javax.management.remote.JMXConnector创建的。我们打开了一些javax.management.remote.JMXConnector来访问其他服务器中的MBean。但没有关闭它们。关闭这些JMXConnector实例后，线程就消失了。
javax.management.remote.JMXConnector正在使用xnio与MBean进行通信。它将在打开时创建XnioWorker，XnioWorker将创建Remoting“端点”任务线程。所以问题不是由EJB引起的。