jmc线程转储_Java线程转储– VisualVM，jstack，kill -3，jcmd

jmc线程转储

Java Thread dump is list of all the threads active in the JVM.

Java线程转储是JVM中所有活动线程的列表。

Java线程转储 (Java Thread Dump)

Java thread dump is very helpful in analyzing bottlenecks in the application and deadlock situations.

Java线程转储对于分析应用程序和死锁情况下的瓶颈非常有帮助。

Here we will learn multiple ways through which we can generate thread dump for a java program. These instructions are valid for *nix operating systems but in windows the steps might be little different.

在这里，我们将学习可以为Java程序生成线程转储的多种方法。这些说明适用于* nix操作系统，但在Windows中，步骤可能稍有不同。

VisualVM Profiler: If you are analyzing application for slowness, you must use a profiler. We can generate thread dump for any process using VisualVM profiler very easily. You just need to right click on the running process and click on “Thread Dump” option to generate it.VisualVM Profiler ：如果要分析应用程序的运行速度，则必须使用探查器。我们可以很容易地使用VisualVM Profiler为任何进程生成线程转储。您只需要右键单击运行的进程，然后单击“ Thread Dump”选项即可生成它。
jstack: Java comes with jstack tool through which we can generate thread dump for a java process. This is a two step process.
1. Find out the PID of the java process using ps -eaf | grep java command
2. Run jstack tool as jstack PID to generate the thread dump output to console, you can append thread dump output to file using command “jstack PID >> mydumps.tdump“
jstack ：Java附带了jstack工具，通过它我们可以为Java进程生成线程转储。这是一个两步过程。
1. 使用ps -eaf | grep java查找Java进程的PID。 ps -eaf | grep java命令
2. 将jstack工具作为jstack PID运行以将线程转储输出生成到控制台，您可以使用命令“ jstack PID >> mydumps.tdump ”将线程转储输出附加到文件。
We can use kill -3 PID command to generate the thread dump. This is slightly different from other ways to generate thread dump. When kill command is issued, thread dump is generated to the System out of the program. So if it’s a java program with console as system out, the thread dump will get printed on the console. If the java program is a Tomcat server with system out as catalina.out, then thread dump will be generated in the file.我们可以使用kill -3 PID命令生成线程转储。这与生成线程转储的其他方式稍有不同。当发出kill命令时，线程转储会从程序中生成到系统。因此，如果它是带有控制台作为系统输出的Java程序，则线程转储将被打印在控制台上。如果Java程序是系统输出为catalina.out的Tomcat服务器，则将在文件中生成线程转储。
Java 8 has introduced jcmd utility. You should use this instead of jstack if you are on Java 8 or higher. Command to generate thread dump using jcmd is jcmd PID Thread.print.Java 8引入了jcmd实用程序。如果您使用的是Java 8或更高版本，则应使用它而不是jstack。使用jcmd生成线程转储的命令是jcmd PID Thread.print 。

Above are four different ways to generate thread dump in java. Usually I prefer jstack or jcmd command to generate thread dump and analyze. Note that whatever way you choose, thread dump will always be the same.

上面是用Java生成线程转储的四种不同方法。通常，我更喜欢使用jstack或jcmd命令来生成线程转储和分析。请注意，无论选择哪种方式，线程转储都将始终相同。

Java线程转储示例 (Java Thread Dump Example)

In my last post, I explained about java Timer, here is a thread dump generated for the same program.

在上一篇文章中，我解释了有关java Timer的问题，这是为同一程序生成的线程转储。

2012-12-26 22:28:39
Full thread dump Java HotSpot(TM) 64-Bit Server VM (23.5-b02 mixed mode):"Attach Listener" daemon prio=5 tid=0x00007fb7d8000000 nid=0x4207 waiting on condition [0x0000000000000000]java.lang.Thread.State: RUNNABLE"Timer-0" daemon prio=5 tid=0x00007fb7d4867000 nid=0x5503 waiting on condition [0x00000001604d9000]java.lang.Thread.State: TIMED_WAITING (sleeping)at java.lang.Thread.sleep(Native Method)at com.journaldev.threads.MyTimerTask.completeTask(MyTimerTask.java:19)at com.journaldev.threads.MyTimerTask.run(MyTimerTask.java:12)at java.util.TimerThread.mainLoop(Timer.java:555)at java.util.TimerThread.run(Timer.java:505)"Service Thread" daemon prio=5 tid=0x00007fb7d482c000 nid=0x5303 runnable [0x0000000000000000]java.lang.Thread.State: RUNNABLE"C2 CompilerThread1" daemon prio=5 tid=0x00007fb7d482b800 nid=0x5203 waiting on condition [0x0000000000000000]java.lang.Thread.State: RUNNABLE"C2 CompilerThread0" daemon prio=5 tid=0x00007fb7d4829800 nid=0x5103 waiting on condition [0x0000000000000000]java.lang.Thread.State: RUNNABLE"Signal Dispatcher" daemon prio=5 tid=0x00007fb7d4828800 nid=0x5003 runnable [0x0000000000000000]java.lang.Thread.State: RUNNABLE"Finalizer" daemon prio=5 tid=0x00007fb7d4812000 nid=0x3f03 in Object.wait() [0x000000015fd26000]java.lang.Thread.State: WAITING (on object monitor)at java.lang.Object.wait(Native Method)- waiting on <0x0000000140a25798> (a java.lang.ref.ReferenceQueue$Lock)at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)- locked <0x0000000140a25798> (a java.lang.ref.ReferenceQueue$Lock)at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:177)"Reference Handler" daemon prio=5 tid=0x00007fb7d4811800 nid=0x3e03 in Object.wait() [0x000000015fc23000]java.lang.Thread.State: WAITING (on object monitor)at java.lang.Object.wait(Native Method)- waiting on <0x0000000140a25320> (a java.lang.ref.Reference$Lock)at java.lang.Object.wait(Object.java:503)at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)- locked <0x0000000140a25320> (a java.lang.ref.Reference$Lock)"main" prio=5 tid=0x00007fb7d5000800 nid=0x1703 waiting on condition [0x0000000106116000]java.lang.Thread.State: TIMED_WAITING (sleeping)at java.lang.Thread.sleep(Native Method)at com.journaldev.threads.MyTimerTask.main(MyTimerTask.java:33)"VM Thread" prio=5 tid=0x00007fb7d480f000 nid=0x3d03 runnable "GC task thread#0 (ParallelGC)" prio=5 tid=0x00007fb7d500d800 nid=0x3503 runnable "GC task thread#1 (ParallelGC)" prio=5 tid=0x00007fb7d500e000 nid=0x3603 runnable "GC task thread#2 (ParallelGC)" prio=5 tid=0x00007fb7d5800000 nid=0x3703 runnable "GC task thread#3 (ParallelGC)" prio=5 tid=0x00007fb7d5801000 nid=0x3803 runnable "GC task thread#4 (ParallelGC)" prio=5 tid=0x00007fb7d5801800 nid=0x3903 runnable "GC task thread#5 (ParallelGC)" prio=5 tid=0x00007fb7d5802000 nid=0x3a03 runnable "GC task thread#6 (ParallelGC)" prio=5 tid=0x00007fb7d5802800 nid=0x3b03 runnable "GC task thread#7 (ParallelGC)" prio=5 tid=0x00007fb7d5803800 nid=0x3c03 runnable "VM Periodic Task Thread" prio=5 tid=0x00007fb7d481e800 nid=0x5403 waiting on condition JNI global references: 116

Thread dump is the list of all the threads, every entry shows information about thread which includes following in the order of appearance.

线程转储是所有线程的列表，每个条目都显示有关线程的信息，其中包括按照出现顺序的信息。

Thread Name: Name of the Thread线程名称： 线程名称
Thread Priority: Priority of the thread线程优先级： 线程的优先级
Thread ID: Represents the unique ID of the Thread线程ID ：代表线程的唯一ID
Thread Status: Provides the current thread state, for example RUNNABLE, WAITING, BLOCKED. While analyzing deadlock look for the blocked threads and resources on which they are trying to acquire lock.线程状态：提供当前线程状态，例如RUNNABLE，WAITING，BLOCKED。分析死锁时，寻找它们试图获取锁的阻塞线程和资源。
Thread callstack: Provides the vital stack information for the thread. This is the place where we can see the locks obtained by Thread and if it’s waiting for any lock.线程调用堆栈：提供线程的重要堆栈信息。在这里，我们可以看到Thread获得的锁以及是否正在等待任何锁。

That’s all for thread dump in java.

这就是Java中的线程转储的全部内容。

翻译自: https://www.journaldev.com/1053/java-thread-dump-visualvm-jstack-kill-3-jcmd

jmc线程转储