We have implemented a feature in our web app that updates the GUI in response to new events in the server by using Play's continuations, just like a chat app. After running it for some time in production we started to experience server hangs, more specifically the http connector of our Glassfish server stopped accepting new requests. A thread dump shows us that all http threads from the http thread pool are waiting for Play Promises to be invoked. Our thread pool has 5 threads (the default number) which means there are 5 clients waiting to be notified and the server cannot accept more http connections unless some of the actual clients closes its connection.
According Play's docs on continuations/request suspension when a request is suspended by calling await() the request's thread should be freed. That's not what is happening here.
Reference: http://www.playframework.org/documentation/1.2.3/asynchronous
I did some research on Play's source code and could not find any hint. Also my code seems to be all right, but I'm not sure (see below). I hope that somebody may point me out to what I might be doing wrong.
Versions:
Play 1.2.3
Glassfish 3.1.1
Source code:
public class Sessions extends Controller {
public static void waitFor(Query query, long lastSessionId, List<Long> openSessionIds) {
String clientId = request.remoteAddress;
List<Session> sessions = query
.with(new UpdatedSessions(lastSessionId, openSessionIds))
.execute();
Logger.info("%s -> Updated sessions since %s + %s: %s", clientId, lastSessionId, openSessionIds, sessions);
while(sessions.isEmpty()) {
List<Long> ids = await(MailBox.watch(query, clientId));
Logger.info("%s -> Received ids: %s", clientId, ids);
sessions = query.with(new SessionIds(ids)).execute();
Logger.info("%s -> Queried sessions: %s", clientId, sessions);
}
Logger.info("%s -> Delivering %s", clientId, sessions);
List<Tile> tiles = Tile.forGates(query.gates());
render(sessions, tiles);
}
}
public class MailBox {
private static List<Promise<List<Long>>> promises = Collections.synchronizedList(new ArrayList<Promise<List<Long>>>());
public static Future<List<Long>> watch(Query query, String clientId) {
Logger.info("Mailbox.watch(%s, %s)", query, clientId);
Promise<List<Long>> promise = new Promise<List<Long>>();
promises.add(promise);
return promise;
}
public static void put(final long sessionId) {
Logger.info("Mailbox.put(%s): promises=%s", sessionId, promises);
if(promises.isEmpty())
return;
final List<Promise<List<Long>>> targets = seizePromises();
new Thread() {
@Override
public void run() {
// It's a list because we will accumulate ids before notifying the waiting clients
List<Long> ids = Arrays.asList(sessionId);
Logger.info("Mailbox.put(%s): target=%s", sessionId, targets);
for(Promise<List<Long>> promise : targets)
promise.invoke(ids);
}
}.start();
}
private static List<Promise<List<Long>>> seizePromises() {
List<Promise<List<Long>>> result = new ArrayList<Promise<List<Long>>>();
synchronized (promises) {
result.addAll(promises);
promises.clear();
}
return result;
}
}
Thread dump (trimmed, see the full dump here http://pastebin.com/1TdV1njv):
2011-11-22 10:42:00
Full thread dump OpenJDK 64-Bit Server VM (20.0-b11 mixed mode):
"RMI TCP Connection(idle)" daemon prio=10 tid=0x0000000000ffe000 nid=0xca0 waiting on condition [0x00007f5cf1fa4000]
java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000e27f9300> (a java.util.concurrent.SynchronousQueue$TransferStack)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:226)
at java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:453)
at java.util.concurrent.SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:352)
at java.util.concurrent.SynchronousQueue.poll(SynchronousQueue.java:903)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1043)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1103)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- None
"JMX server connection timeout 87" daemon prio=10 tid=0x00000000012d6000 nid=0xc9e in Object.wait() [0x00007f5cebefd000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000000fe5242d8> (a [I)
at com.sun.jmx.remote.internal.ServerCommunicatorAdmin$Timeout.run(ServerCommunicatorAdmin.java:168)
- locked <0x00000000fe5242d8> (a [I)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- None
"RMI TCP Connection(3)-127.0.0.1" daemon prio=10 tid=0x0000000001374000 nid=0xc9c runnable [0x00007f5cf20a5000]
java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:146)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
at java.io.BufferedInputStream.read(BufferedInputStream.java:254)
- locked <0x00000000fe5a2010> (a java.io.BufferedInputStream)
at java.io.FilterInputStream.read(FilterInputStream.java:83)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:808)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:667)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- <0x00000000fe521bc8> (a java.util.concurrent.ThreadPoolExecutor$Worker)
"RMI TCP Accept-0" daemon prio=10 tid=0x0000000001375000 nid=0xc99 runnable [0x00007f5ceb3f2000]
java.lang.Thread.State: RUNNABLE
at java.net.PlainSocketImpl.socketAccept(Native Method)
at java.net.AbstractPlainSocketImpl.accept(AbstractPlainSocketImpl.java:375)
at java.net.ServerSocket.implAccept(ServerSocket.java:470)
at java.net.ServerSocket.accept(ServerSocket.java:438)
at sun.management.jmxremote.LocalRMIServerSocketFactory$1.accept(LocalRMIServerSocketFactory.java:52)
at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.executeAcceptLoop(TCPTransport.java:387)
at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.run(TCPTransport.java:359)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- None
"Attach Listener" daemon prio=10 tid=0x0000000001341800 nid=0xc98 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"http-thread-pool-8080(5)" daemon prio=10 tid=0x00007f5cec119800 nid=0xbb5 waiting on condition [0x00007f5cea8e6000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000fe4d6bb8> (a java.util.concurrent.CountDownLatch$Sync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:838)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:998)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:235)
at play.libs.F$Promise.get(F.java:46)
at play.Invoker.invokeInThread(Invoker.java:73)
at play.server.ServletWrapper.service(ServletWrapper.java:130)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- <0x00000000e39f4eb0> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
"http-thread-pool-8080(4)" daemon prio=10 tid=0x00007f5cec142800 nid=0xbb4 waiting on condition [0x00007f5cea9e7000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000f6ff9e90> (a java.util.concurrent.CountDownLatch$Sync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:838)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:998)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:235)
at play.libs.F$Promise.get(F.java:46)
at play.Invoker.invokeInThread(Invoker.java:73)
at play.server.ServletWrapper.service(ServletWrapper.java:130)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- <0x00000000fe4a3b90> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
"http-thread-pool-8080(3)" daemon prio=10 tid=0x00007f5cec140800 nid=0xbb3 waiting on condition [0x00007f5ceaae8000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000fe4a3288> (a java.util.concurrent.CountDownLatch$Sync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:838)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:998)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:235)
at play.libs.F$Promise.get(F.java:46)
at play.Invoker.invokeInThread(Invoker.java:73)
at play.server.ServletWrapper.service(ServletWrapper.java:130)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- <0x00000000e28c0fd0> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
"http-thread-pool-8080(2)" daemon prio=10 tid=0x00007f5cec02d000 nid=0xbb2 waiting on condition [0x00007f5ceabe9000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000f72411d8> (a java.util.concurrent.CountDownLatch$Sync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:838)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:998)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:235)
at play.libs.F$Promise.get(F.java:46)
at play.Invoker.invokeInThread(Invoker.java:73)
at play.server.ServletWrapper.service(ServletWrapper.java:130)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- <0x00000000f63b3958> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
"http-thread-pool-8080(1)" daemon prio=10 tid=0x00007f5cec02c800 nid=0xbb1 waiting on condition [0x00007f5ceb0ee000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000f7424bd0> (a java.util.concurrent.CountDownLatch$Sync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:838)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:998)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:235)
at play.libs.F$Promise.get(F.java:46)
at play.Invoker.invokeInThread(Invoker.java:73)
at play.server.ServletWrapper.service(ServletWrapper.java:130)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- <0x00000000f63c78b0> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
"SCR Component Actor" daemon prio=10 tid=0x00007f5ce472d000 nid=0xba8 in Object.wait() [0x00007f5ceadec000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000000e260c920> (a java.util.LinkedList)
at java.lang.Object.wait(Object.java:502)
at org.apache.felix.scr.impl.ComponentActorThread.run(ComponentActorThread.java:74)
- locked <0x00000000e260c920> (a java.util.LinkedList)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- None
"pool-7-thread-1" prio=10 tid=0x00007f5ce5134800 nid=0xba7 waiting on condition [0x00007f5ceaceb000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000e260cb78> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:386)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1043)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1103)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:679)
Locked ownable synchronizers:
- None
As Guillaume has mentioned on the Google Groups site, this is because Play continuations only work on the inbuilt Netty server. You are entirely correct that this information is lacking from the documentation, but it is simply a case that only using Netty does Play have control over the request thread. For all the other servers, Play needs to create a wrapper around the servlet API, meaning that a thread cannot be held by Play.
Unfortunately, this is one of the trade-offs when using Play deployed to anything other than the preferred platform.
来源：https://stackoverflow.com/questions/8228574/plays-continuations-holding-http-threads