Hi, are you running this application on Windows? There is a known situation <https://github.com/akka/akka/issues/16942> where high CPU usage might occur when using TCP with akka IO.
On Tue, Apr 14, 2015 at 7:28 AM, Akara Sucharitakul < akara.sucharita...@gmail.com> wrote: > Scala 2.11.6, Akka 2.3.9, Spray 1.3.2. > > When testing a particular workload, we ran into CPU spikes. The avg CPU > load is less than 5% but about 6-7 minutes into the run, we start to see > CPU spiking to near 100% lasting for several seconds. This repeats itself > every 6-7 minutes. We can't correlate this with a particular GC activity > just yet. We tested against Java 7_45 but tried Java 8 without much change. > > Spray is configured on the default-dispatcher (Spray default). > > Trying to capture thread dumps at the time spikes happening reveal 9 > threads spinning on the followings: > > "default-akka.actor.default-dispatcher-11" prio=10 tid=0x0000000001b2b800 > nid=0x3752 runnable [0x00007f1191d40000] > java.lang.Thread.State: RUNNABLE > at > akka.io.DirectByteBufferPool.takeBufferFromPool(DirectByteBufferPool.scala:41) > at akka.io.DirectByteBufferPool.acquire(DirectByteBufferPool.scala:31) > at akka.io.TcpConnection.doRead(TcpConnection.scala:231) > at > akka.io.TcpConnection$$anonfun$connected$1.applyOrElse(TcpConnection.scala:87) > at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:171) > at akka.actor.Actor$class.aroundReceive(Actor.scala:465) > at akka.io.TcpConnection.aroundReceive(TcpConnection.scala:28) > at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516) > at akka.actor.ActorCell.invoke(ActorCell.scala:487) > at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:254) > at akka.dispatch.Mailbox.run(Mailbox.scala:221) > at akka.dispatch.Mailbox.exec(Mailbox.scala:231) > at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260) > at > scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339) > at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979) > at > scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107) > > 2 threads show this spinning: > > "default-akka.actor.default-dispatcher-8" prio=10 tid=0x0000000001d6f000 > nid=0x374f runnable [0x00007f11928d2000] > java.lang.Thread.State: RUNNABLE > at > akka.io.DirectByteBufferPool.offerBufferToPool(DirectByteBufferPool.scala:66) > at akka.io.DirectByteBufferPool.release(DirectByteBufferPool.scala:34) > at akka.io.TcpConnection.doRead(TcpConnection.scala:245) > at > akka.io.TcpConnection$$anonfun$connected$1.applyOrElse(TcpConnection.scala:87) > at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:171) > at akka.actor.Actor$class.aroundReceive(Actor.scala:465) > at akka.io.TcpConnection.aroundReceive(TcpConnection.scala:28) > at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516) > at akka.actor.ActorCell.invoke(ActorCell.scala:487) > at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:254) > at akka.dispatch.Mailbox.run(Mailbox.scala:221) > at akka.dispatch.Mailbox.exec(Mailbox.scala:231) > at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260) > at > scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339) > at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979) > at > scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107) > > 1 thread is on I/O: > > "default-akka.actor.default-dispatcher-4" prio=10 tid=0x0000000001be2800 > nid=0x36ff runnable [0x00007f11924b0000] > java.lang.Thread.State: RUNNABLE > at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:295) > - locked <0x00000007d3b7e940> (a java.lang.Object) > at akka.io.TcpConnection.innerRead$1(TcpConnection.scala:216) > at akka.io.TcpConnection.doRead(TcpConnection.scala:232) > at > akka.io.TcpConnection$$anonfun$connected$1.applyOrElse(TcpConnection.scala:87) > at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:171) > at akka.actor.Actor$class.aroundReceive(Actor.scala:465) > at akka.io.TcpConnection.aroundReceive(TcpConnection.scala:28) > at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516) > at akka.actor.ActorCell.invoke(ActorCell.scala:487) > at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:254) > at akka.dispatch.Mailbox.run(Mailbox.scala:221) > at akka.dispatch.Mailbox.exec(Mailbox.scala:231) > at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260) > at > scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339) > at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979) > at > scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107) > > All in all, during this time there is no app logic being executed on the > default dispatcher at all (12 threads on the default-dispatcher). > > For reference, here's the takeBufferFromPool implementation: > > @tailrec > private final def takeBufferFromPool(): ByteBuffer = > if (locked.compareAndSet(false, true)) { > val buffer = > try if (buffersInPool > 0) { > buffersInPool -= 1 > pool(buffersInPool) > } else null > finally locked.set(false) > > // allocate new and clear outside the lock > if (buffer == null) > allocate(defaultBufferSize) > else { > buffer.clear() > buffer > } > } else takeBufferFromPool() // spin while locked > > > It seems like some thread is holding *locked* (AtomicBoolean) to true > causing the other threads to spin, but I do not seem to find the offending > code. > > Now to the set of questions: > > 1. Using thread-pool-executor instead of fork-join-executor prevents > the spikes from happening. Anybody running into similar issues with > fork-join-executor? Any know bug in the Scala ForkJoinPool? > 2. I don't seem to find a way to use the Java 8 or Java 7 ForkJoinPool > directly in the Akka docs. Is there a way I can test it out? > 3. Any other thoughts? > > Thanks in advance! > -Akara > > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to akka-user+unsubscr...@googlegroups.com. > To post to this group, send email to akka-user@googlegroups.com. > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > -- Martynas Mickevičius Typesafe <http://typesafe.com/> – Reactive <http://www.reactivemanifesto.org/> Apps on the JVM -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. 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