如何解决/调试 JVM 崩溃的最佳方法 (SIGSEGV)

问题描述

我真的很迷茫，我不知道如何面对和解决我的问题.我有一段简单的 Java 代码，导致 JVM 崩溃:

I'm really lost and I don't know how to face and solve my problem. I have a piece of simple Java Code, which leads to a JVM crash:

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00000001057ce9d4, pid=10727, tid=18947
#
# JRE version: Java(TM) SE Runtime Environment (8.0_73-b02) (build 1.8.0_73-b02)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.73-b02 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# V  [libjvm.dylib+0x3ce9d4]  PhaseIdealLoop::idom_no_update(Node*) const+0x12
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
#

---------------  T H R E A D  ---------------

Current thread (0x00007feeef003800):  JavaThread "C2 CompilerThread0" daemon [_thread_in_native, id=18947, stack(0x0000700000ec4000,0x0000700000fc4000)]

siginfo: si_signo: 11 (SIGSEGV), si_code: 1 (SEGV_MAPERR), si_addr: 0x0000000000000008

我不知道如何解决这个问题.该程序非常简单，它通过 Kafka 接收消息并根据收到的消息触发任务.如果我添加两个不同的任务，程序会在 900 - 1,500 条消息后崩溃.所有消息都是相同的，并且程序不使用任何 JNI 东西(据我所知，使用过的 3rd 方库也不使用任何 JNI).

I have no idea on how to solve the problem. The program is pretty simple, it receives a message through Kafka and triggers tasks based on the message received. If I add two different tasks, the program crashes after 900 - 1,500 messages. All of the messages are the same and the program does not use any JNI stuff (the used 3rd party libraries don't use any JNI as well, as far as I'm informed).

我从未遇到过这个问题，但我希望/需要找到一种方法来找出问题所在.我已经使用过其他版本的 JVM(Java 8.0_66、8.0_73-b02 和 8.0_74-b02).那么我能做什么呢?非常感谢！

I never faced this problem, but I'd love/need to find a way on how to figure out what the problem is. I already used other versions of the JVM (Java 8.0_66, 8.0_73-b02, and 8.0_74-b02). So what can I do? Thank you so much!

编辑(1):有时我也会收到以下错误/信息:

EDIT (1): Sometimes I also get the following error/info:

...
# JRE version: Java(TM) SE Runtime Environment (8.0_73-b02) (build 1.8.0_73-b02)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.73-b02 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# V  [libjvm.dylib+0x3ce9d4]
...

编辑 (2):我将 Java 版本更新为 8.0_74.错误仍然存​​在:(.

EDIT (2): I updated my Java version to 8.0_74. The error is still there :(.

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00000001073cdef8, pid=11227, tid=19715
#
# JRE version: Java(TM) SE Runtime Environment (8.0_74-b02) (build 1.8.0_74-b02)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.74-b02 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# V  [libjvm.dylib+0x3cdef8]  PhaseIdealLoop::idom_no_update(Node*) const+0x12
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
#

---------------  T H R E A D  ---------------

Current thread (0x00007f89e481c800):  JavaThread "C2 CompilerThread1" daemon [_thread_in_native, id=19715, stack(0x000070000104a000,0x000070000114a000)]

siginfo: si_signo: 11 (SIGSEGV), si_code: 1 (SEGV_MAPERR), si_addr: 0x0000000000000008

编辑(3):核心转储

所以最后我创建了一个核心转储并将其加载到 Java VisualVM 中(我无法使用 DROY 提供的解决方案，因为调用 jmap 会导致另一个错误:附加到核心文件时出错:无法附加到核心文件").使用 VisualVM 创建的线程转储结果:

So finally I created a core dump and loaded it into Java VisualVM (I could not use the solution presented by DROY because calling jmap lead to another error: "Error attaching to core file: Can't attach to the core file"). The threaddump created with VisualVM results in:

Thread 30239 "Keep-Alive-Timer": (state = BLOCKED)
    at java.lang.Thread.sleep(Native Method)
    at sun.net.www.http.KeepAliveCache.run(KeepAliveCache.java:172)
    at java.lang.Thread.run(Thread.java:745)

Thread 29699 "threadDeathWatcher-4-1": (state = BLOCKED)
    at java.lang.Thread.sleep(Native Method)
    at io.netty.util.ThreadDeathWatcher$Watcher.run(ThreadDeathWatcher.java:137)
    at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)
    at java.lang.Thread.run(Thread.java:745)

Thread 26635 "nioEventLoopGroup-3-1": (state = IN_NATIVE)
    at sun.nio.ch.KQueueArrayWrapper.kevent0(Native Method)
    at sun.nio.ch.KQueueArrayWrapper.poll(KQueueArrayWrapper.java:198)
    at sun.nio.ch.KQueueSelectorImpl.doSelect(KQueueSelectorImpl.java:117)
    at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
    - locked <0x00000006c049ec98> (a io.netty.channel.nio.SelectedSelectionKeySet)
    - locked <0x00000006c049ec88> (a java.util.Collections$UnmodifiableSet)
    - locked <0x00000006c049ecb8> (a sun.nio.ch.KQueueSelectorImpl)
    at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
    at io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:622)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:310)
    at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:110)
    at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)
    at java.lang.Thread.run(Thread.java:745)

Thread 29187 "pool-3-thread-1": (state = BLOCKED)
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at kafka.consumer.ConsumerIterator.makeNext(ConsumerIterator.scala:63)
    at kafka.consumer.ConsumerIterator.makeNext(ConsumerIterator.scala:33)
    at kafka.utils.IteratorTemplate.maybeComputeNext(IteratorTemplate.scala:66)
    at kafka.utils.IteratorTemplate.hasNext(IteratorTemplate.scala:58)
    at com.sosse.common.messaging.DefaultHandler.doRun(DefaultHandler.java:22)
    at com.sosse.common.concurrency.DefaultRunnable.run(DefaultRunnable.java:11)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

Thread 28675 "pool-4-thread-1": (state = BLOCKED)
    at java.lang.Thread.sleep(Native Method)
    at io.netty.util.HashedWheelTimer$Worker.waitForNextTick(HashedWheelTimer.java:461)
    at io.netty.util.HashedWheelTimer$Worker.run(HashedWheelTimer.java:360)
    at java.lang.Thread.run(Thread.java:745)

Thread 28163 "ConsumerFetcherThread-analytics-group_Philipp.local-1458441725398-581eabc3-0-0": (state = IN_NATIVE)
    at sun.nio.ch.Net.poll(Native Method)
    at sun.nio.ch.SocketChannelImpl.poll(SocketChannelImpl.java:954)
    - locked <0x00000006c056d538> (a java.lang.Object)
    at sun.nio.ch.SocketAdaptor$SocketInputStream.read(SocketAdaptor.java:204)
    - locked <0x00000006c056d5b8> (a java.lang.Object)
    at sun.nio.ch.ChannelInputStream.read(ChannelInputStream.java:103)
    - locked <0x00000006c056d5f8> (a sun.nio.ch.SocketAdaptor$SocketInputStream)
    at java.nio.channels.Channels$ReadableByteChannelImpl.read(Channels.java:385)
    - locked <0x00000006c056d618> (a java.lang.Object)
    at kafka.utils.Utils$.read(Utils.scala:380)
    at kafka.network.BoundedByteBufferReceive.readFrom(BoundedByteBufferReceive.scala:54)
    at kafka.network.Receive$class.readCompletely(Transmission.scala:56)
    at kafka.network.BoundedByteBufferReceive.readCompletely(BoundedByteBufferReceive.scala:29)
    at kafka.network.BlockingChannel.receive(BlockingChannel.scala:111)
    at kafka.consumer.SimpleConsumer.liftedTree1$1(SimpleConsumer.scala:71)
    at kafka.consumer.SimpleConsumer.kafka$consumer$SimpleConsumer$$sendRequest(SimpleConsumer.scala:68)
    - locked <0x00000006c056d6e0> (a java.lang.Object)
    at kafka.consumer.SimpleConsumer$$anonfun$fetch$1$$anonfun$apply$mcV$sp$1.apply$mcV$sp(SimpleConsumer.scala:112)
    at kafka.consumer.SimpleConsumer$$anonfun$fetch$1$$anonfun$apply$mcV$sp$1.apply(SimpleConsumer.scala:112)
    at kafka.consumer.SimpleConsumer$$anonfun$fetch$1$$anonfun$apply$mcV$sp$1.apply(SimpleConsumer.scala:112)
    at kafka.metrics.KafkaTimer.time(KafkaTimer.scala:33)
    at kafka.consumer.SimpleConsumer$$anonfun$fetch$1.apply$mcV$sp(SimpleConsumer.scala:111)
    at kafka.consumer.SimpleConsumer$$anonfun$fetch$1.apply(SimpleConsumer.scala:111)
    at kafka.consumer.SimpleConsumer$$anonfun$fetch$1.apply(SimpleConsumer.scala:111)
    at kafka.metrics.KafkaTimer.time(KafkaTimer.scala:33)
    at kafka.consumer.SimpleConsumer.fetch(SimpleConsumer.scala:110)
    at kafka.server.AbstractFetcherThread.processFetchRequest(AbstractFetcherThread.scala:94)
    at kafka.server.AbstractFetcherThread.doWork(AbstractFetcherThread.scala:86)
    at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:60)

Thread 27651 "analytics-group_Philipp.local-1458441725398-581eabc3-leader-finder-thread": (state = BLOCKED)
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at kafka.consumer.ConsumerFetcherManager$LeaderFinderThread.doWork(ConsumerFetcherManager.scala:61)
    at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:60)

Thread 27139 "analytics-group_Philipp.local-1458441725398-581eabc3_watcher_executor": (state = BLOCKED)
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2163)
    at kafka.consumer.ZookeeperConsumerConnector$ZKRebalancerListener$$anon$1.run(ZookeeperConsumerConnector.scala:544)

Thread 26115 "kafka-consumer-scheduler-0": (state = BLOCKED)
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
    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)

Thread 25603 "main-EventThread": (state = BLOCKED)
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:494)

Thread 25091 "main-SendThread(localhost:2181)": (state = IN_NATIVE)
    at sun.nio.ch.KQueueArrayWrapper.kevent0(Native Method)
    at sun.nio.ch.KQueueArrayWrapper.poll(KQueueArrayWrapper.java:198)
    at sun.nio.ch.KQueueSelectorImpl.doSelect(KQueueSelectorImpl.java:117)
    at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
    - locked <0x00000006c0022c50> (a sun.nio.ch.Util$2)
    - locked <0x00000006c0022c60> (a java.util.Collections$UnmodifiableSet)
    - locked <0x00000006c0022c00> (a sun.nio.ch.KQueueSelectorImpl)
    at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
    at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:349)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1081)

Thread 24579 "ZkClient-EventThread-16-localhost:2181": (state = BLOCKED)
    at sun.misc.Unsafe.park(Native Method)
    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 org.I0Itec.zkclient.ZkEventThread.run(ZkEventThread.java:67)

Thread 24067 "metrics-meter-tick-thread-2": (state = BLOCKED)
    at sun.misc.Unsafe.park(Native Method)
    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)

Thread 23555 "metrics-meter-tick-thread-1": (state = BLOCKED)
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
    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)

Thread 23303 "pool-1-thread-1": (state = BLOCKED)
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
    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)

VM Thread 20995 "Service Thread": (state = BLOCKED)

VM Thread 20483 "C1 CompilerThread3": (state = BLOCKED)

VM Thread 19971 "C2 CompilerThread2": (state = IN_NATIVE)

VM Thread 19459 "C2 CompilerThread1": (state = IN_NATIVE)

VM Thread 18947 "C2 CompilerThread0": (state = IN_NATIVE)

Thread 15887 "Signal Dispatcher": (state = BLOCKED)

Thread 14339 "Finalizer": (state = BLOCKED)
    at java.lang.Object.wait(Native Method)
    - waiting on <0x00000006c005fa88> (a java.lang.ref.ReferenceQueue$Lock)
    at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
    - locked <0x00000006c005fa88> (a java.lang.ref.ReferenceQueue$Lock)
    at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:164)
    at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)

Thread 13827 "Reference Handler": (state = BLOCKED)
    at java.lang.Object.wait(Native Method)
    - waiting on <0x00000006c0029358> (a java.lang.ref.Reference$Lock)
    at java.lang.Object.wait(Object.java:502)
    at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
    - locked <0x00000006c0029358> (a java.lang.ref.Reference$Lock)
    at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

Thread 2823 "main": (state = BLOCKED)
    at java.lang.Thread.sleep(Native Method)
    at com.sosse.analytics.ActivityProducer.sleep(ActivityProducer.java:110)
    at com.sosse.analytics.DemoMain$1.startApplication(DemoMain.java:37)
    at com.sosse.common.application.DefaultApplication.start(DefaultApplication.java:166)
    - locked <0x00000006c00e6080> (a java.lang.Thread)
    at com.sosse.common.application.DefaultApplication.start(DefaultApplication.java:118)
    at com.sosse.analytics.DemoMain.main(DemoMain.java:48)

编辑(4):源代码反序列化器

EDIT (4): Source Code Deserializer

public static Object[] deserialize(final JsonElement jsonElement, final JsonDeserializationContext context, final BiFunction<Class<?>, JsonElement, Serializable[]> timeSeriesDeserializer) {
    final JsonObject jsonObject = jsonElement.getAsJsonObject();

    // get the important classes
    final Class<?> bucketContent = resolveClass("bucketContent", jsonObject, context);

    // configuration
    final TimeUnit timeUnit = context.deserialize(jsonObject.get("timeUnit"), TimeUnit.class);
    final int bucketSize = context.deserialize(jsonObject.get("bucketSize"), int.class);
    final boolean fillNumberWithZero = context.deserialize(jsonObject.get("fillNumberWithZero"), boolean.class);

    // the values
    final Long now = context.deserialize(jsonObject.get("now"), Long.class);
    final Serializable[] timeSeries = timeSeriesDeserializer.apply(bucketContent, jsonObject.get("timeSeries"));

    @SuppressWarnings("unchecked")
    final BucketTimeSeriesConfig config = new BucketTimeSeriesConfig(bucketContent, timeUnit, timeSeries.length, bucketSize, fillNumberWithZero);
    return new Object[]{config, timeSeries, now};
}

推荐答案

崩溃报告告诉 JIT 编译器线程发生了错误:

The crash report tells the error has happened in JIT compiler thread:

Current thread (0x00007f89e481c800):  JavaThread "C2 CompilerThread1"

采取以下步骤诊断编译器问题:

Take the following steps do diagnose compiler problems:

1. 试用 JDK 9 EA 中可用的最新 JVM 构建:https://jdk9.java.网络/下载/

如果问题消失，您可以继续使用此版本，或者尝试找到解决问题的确切提交，然后将其反向移植到 JDK 8.如何反向移植修复以及如何自己构建 HotSpot - 这是一个单独的主题，但我可以告诉你是否有兴趣.

If the problem disappears, you can either stay with this version or try to locate the exact commit that solves the issue and then backport it to JDK 8. How to backport fixes and how to build HotSpot yourself - it's a separate topic, but I can tell if you're interested.

如果问题仍然存在，请尝试找到有问题的方法并将其从编译中排除.

If the problem persists, try to find a problematic method and exclude it from compilation.

Current CompileTask: C2: 114667 5303 4 com.sosse.time.timeseries.gson.TypeConverterHelper::deserialize (157 bytes)

在您的情况下，它似乎无法编译 TypeConverterHelper.deserialize().添加以下 JVM 选项以排除此特定方法:

Looks like in your case it fails compiling TypeConverterHelper.deserialize(). Add the following JVM option to exclude this particular method:

-XX:CompileCommand=exclude,com.sosse.time.timeseries.gson.TypeConverterHelper::deserialize

-XX:CompileCommand=exclude,com.sosse.time.timeseries.gson.*::*

-XX:-DoEscapeAnalysis
-XX:LoopUnrollLimit=0
-XX:-PartialPeelLoop
-XX:-UseLoopPredicate
-XX:-LoopUnswitching
-XX:-ReassociateInvariants
-XX:MaxInlineLevel=1
-XX:-IncrementalInline
-XX:-RangeCheckElimination
-XX:-EliminateAllocations
-XX:-UseTypeProfile
-XX:AliasLevel=0

-XX:+UnlockDiagnosticVMOptions -XX:+LogCompilation

Product/Category: HotSpot Virtual Machine (errors)
Subcategory:      J2SE Server Compiler