thread

查看当前线程信息,查看线程的堆栈

参数说明

参数名称 参数说明
id 线程id
[n:] 指定最忙的前N个线程并打印堆栈
[b] 找出当前阻塞其他线程的线程
[i <value>] 指定cpu占比统计的采样间隔,单位为毫秒

cpu占比是如何统计出来的?

这里的cpu统计的是,一段采样间隔内,当前JVM里各个线程所占用的cpu时间占总cpu时间的百分比。其计算方法为:首先进行一次采样,获得所有线程的cpu的使用时间(调用的是java.lang.management.ThreadMXBean#getThreadCpuTime这个接口),然后睡眠一段时间,默认100ms,可以通过-i参数指定,然后再采样一次,最后得出这段时间内各个线程消耗的cpu时间情况,最后算出百分比。

注意: 这个统计也会产生一定的开销(JDK这个接口本身开销比较大),因此会看到as的线程占用一定的百分比,为了降低统计自身的开销带来的影响,可以把采样间隔拉长一些,比如5000毫秒。

如果想看从Java进程启动开始到现在的cpu占比情况:可以使用show-busy-java-threads这个脚本

使用参考

支持一键展示当前最忙的前N个线程并打印堆栈:

  1. $ thread -n 3
  2. "as-command-execute-daemon" Id=29 cpuUsage=75% RUNNABLE
  3. at sun.management.ThreadImpl.dumpThreads0(Native Method)
  4. at sun.management.ThreadImpl.getThreadInfo(ThreadImpl.java:440)
  5. at com.taobao.arthas.core.command.monitor200.ThreadCommand$1.action(ThreadCommand.java:58)
  6. at com.taobao.arthas.core.command.handler.AbstractCommandHandler.execute(AbstractCommandHandler.java:238)
  7. at com.taobao.arthas.core.command.handler.DefaultCommandHandler.handleCommand(DefaultCommandHandler.java:67)
  8. at com.taobao.arthas.core.server.ArthasServer$4.run(ArthasServer.java:276)
  9. at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
  10. at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
  11. at java.lang.Thread.run(Thread.java:745)
  12. Number of locked synchronizers = 1
  13. - java.util.concurrent.ThreadPoolExecutor$Worker@6cd0b6f8
  14. "as-session-expire-daemon" Id=25 cpuUsage=24% TIMED_WAITING
  15. at java.lang.Thread.sleep(Native Method)
  16. at com.taobao.arthas.core.server.DefaultSessionManager$2.run(DefaultSessionManager.java:85)
  17. "Reference Handler" Id=2 cpuUsage=0% WAITING on java.lang.ref.Reference$Lock@69ba0f27
  18. at java.lang.Object.wait(Native Method)
  19. - waiting on java.lang.ref.Reference$Lock@69ba0f27
  20. at java.lang.Object.wait(Object.java:503)
  21. at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)

当没有参数时,显示所有线程的信息。

  1. $ thread
  2. Threads Total: 16, NEW: 0, RUNNABLE: 7, BLOCKED: 0, WAITING: 5, TIMED_WAITING: 4, TERMINATED: 0
  3. ID NAME GROUP PRIORITY STATE %CPU TIME INTERRUPTE DAEMON
  4. 30 as-command-execute-daemon system 9 RUNNABLE 72 0:0 false true
  5. 23 as-session-expire-daemon system 9 TIMED_WAIT 27 0:0 false true
  6. 22 Attach Listener system 9 RUNNABLE 0 0:0 false true
  7. 11 pool-2-thread-1 main 5 TIMED_WAIT 0 0:0 false false
  8. 12 Thread-2 main 5 RUNNABLE 0 0:0 false true
  9. 13 pool-3-thread-1 main 5 TIMED_WAIT 0 0:0 false false
  10. 25 as-selector-daemon system 9 RUNNABLE 0 0:0 false true
  11. 14 Thread-3 main 5 TIMED_WAIT 0 0:0 false false
  12. 26 pool-5-thread-1 system 5 WAITING 0 0:0 false false
  13. 15 Thread-4 main 5 RUNNABLE 0 0:0 false false
  14. 1 main main 5 WAITING 0 0:2 false false
  15. 2 Reference Handler system 10 WAITING 0 0:0 false true
  16. 3 Finalizer system 8 WAITING 0 0:0 false true
  17. 4 Signal Dispatcher system 9 RUNNABLE 0 0:0 false true
  18. 20 NonBlockingInputStreamThread main 5 WAITING 0 0:0 false true
  19. 21 Thread-8 main 5 RUNNABLE 0 0:0 false true

thread id, 显示指定线程的运行堆栈

  1. $ thread 1
  2. "main" Id=1 WAITING on java.util.concurrent.CountDownLatch$Sync@29fafb28
  3. at sun.misc.Unsafe.park(Native Method)
  4. - waiting on java.util.concurrent.CountDownLatch$Sync@29fafb28
  5. at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
  6. at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
  7. at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:997)
  8. at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
  9. at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:231)

thread -b, 找出当前阻塞其他线程的线程

有时候我们发现应用卡住了, 通常是由于某个线程拿住了某个锁, 并且其他线程都在等待这把锁造成的。 为了排查这类问题, arthas提供了thread -b, 一键找出那个罪魁祸首。

  1. $ thread -b
  2. "http-bio-8080-exec-4" Id=27 TIMED_WAITING
  3. at java.lang.Thread.sleep(Native Method)
  4. at test.arthas.TestThreadBlocking.doGet(TestThreadBlocking.java:22)
  5. - locked java.lang.Object@725be470 <---- but blocks 4 other threads!
  6. at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
  7. at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
  8. at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
  9. at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
  10. at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
  11. at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
  12. at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
  13. at test.filter.TestDurexFilter.doFilter(TestDurexFilter.java:46)
  14. at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
  15. at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
  16. at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
  17. at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
  18. at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
  19. at com.taobao.tomcat.valves.ContextLoadFilterValve$FilterChainAdapter.doFilter(ContextLoadFilterValve.java:191)
  20. at com.taobao.eagleeye.EagleEyeFilter.doFilter(EagleEyeFilter.java:81)
  21. at com.taobao.tomcat.valves.ContextLoadFilterValve.invoke(ContextLoadFilterValve.java:150)
  22. at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
  23. at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
  24. at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
  25. at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:429)
  26. at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1085)
  27. at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
  28. at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
  29. - locked org.apache.tomcat.util.net.SocketWrapper@7127ee12
  30. at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  31. at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  32. at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
  33. at java.lang.Thread.run(Thread.java:745)
  34. Number of locked synchronizers = 1
  35. - java.util.concurrent.ThreadPoolExecutor$Worker@31a6493e

注意, 目前只支持找出synchronized关键字阻塞住的线程, 如果是java.util.concurrent.Lock, 目前还不支持。

thread -i, 指定采样时间间隔

  1. $ thread -n 3 -i 1000
  2. "as-command-execute-daemon" Id=4759 cpuUsage=23% RUNNABLE
  3. at sun.management.ThreadImpl.dumpThreads0(Native Method)
  4. at sun.management.ThreadImpl.getThreadInfo(ThreadImpl.java:440)
  5. at com.taobao.arthas.core.command.monitor200.ThreadCommand.processTopBusyThreads(ThreadCommand.java:133)
  6. at com.taobao.arthas.core.command.monitor200.ThreadCommand.process(ThreadCommand.java:79)
  7. at com.taobao.arthas.core.shell.command.impl.AnnotatedCommandImpl.process(AnnotatedCommandImpl.java:96)
  8. at com.taobao.arthas.core.shell.command.impl.AnnotatedCommandImpl.access$100(AnnotatedCommandImpl.java:27)
  9. at com.taobao.arthas.core.shell.command.impl.AnnotatedCommandImpl$ProcessHandler.handle(AnnotatedCommandImpl.java:125)
  10. at com.taobao.arthas.core.shell.command.impl.AnnotatedCommandImpl$ProcessHandler.handle(AnnotatedCommandImpl.java:122)
  11. at com.taobao.arthas.core.shell.system.impl.ProcessImpl$CommandProcessTask.run(ProcessImpl.java:332)
  12. at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  13. at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  14. at java.lang.Thread.run(Thread.java:756)
  15. Number of locked synchronizers = 1
  16. - java.util.concurrent.ThreadPoolExecutor$Worker@546aeec1
  17. ...

thread —state ,查看指定状态的线程

  1. [arthas@28114]$ thread --state WAITING
  2. Threads Total: 15, NEW: 0, RUNNABLE: 7, BLOCKED: 0, WAITING: 5, TIMED_WAITING: 3, TERMINATED: 0
  3. ID NAME GROUP PRIORITY STATE %CPU TIME INTERRU DAEMON
  4. 198 AsyncAppender-Worker-arth system 9 WAITING 0 0:0 false true
  5. 3 Finalizer system 8 WAITING 0 0:0 false true
  6. 14 RMI Scheduler(0) system 9 WAITING 0 0:0 false true
  7. 2 Reference Handler system 10 WAITING 0 0:0 false true
  8. 204 pool-8-thread-1 system 5 WAITING 0 0:0 false false