1 / 10

Troubleshooting Slow or Hung Java Applications

Troubleshooting Slow or Hung Java Applications. Bill Au CBS Interactive http://www.apache.org/~billa/javaone2011/. Agenda. Tools of the Trade Case Studies. Tools – Out Of The Box. jinfo , jmap , jstack , jstat JConsole , VisualVM

talia
Download Presentation

Troubleshooting Slow or Hung Java Applications

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Troubleshooting Slow or Hung Java Applications Bill Au CBS Interactive http://www.apache.org/~billa/javaone2011/

  2. Agenda • Tools of the Trade • Case Studies

  3. Tools – Out Of The Box • jinfo, jmap, jstack, jstat • JConsole, VisualVM • Monitor CPU usage by using JTop plug-in ($JAVA_HOME/demo/management/JTop) • java.lang.management • Platform MXBeans: runtime, operating system, class loading, compilation, garbage collection, memory, thread • Sample code in $JAVA_HOME/demo/management

  4. Tools – java.lang.management • Sample code: import java.lang.management.*; ThreadMXBeantb=ManagementFactory.getThreadMXBean(); if (tb.isThreadCpuTimeSupported()) { long[] tids=tb.getAllThreadIds(); for (long tid : tids) { System.out.println(“cputime:”+tb.getThreadCpuTime(tid)); System.out.println(“usertime:”+tb.getThreadUserTime(tid)); } }

  5. Tools • Garbage collection log • -Xloggc:<filename> • Sizes before and after GC events • Timestamp and duration of GC events • More options to explore: • -XX:+PrintGCDateStamps • -XX:+PrintGCDetails • -XX:+PrintTenuringDistribution • -XX:+PrintGCApplicationsStoppedTime

  6. Tools • Thread dump • kill -3 (or kill –SIGHUP) • JConsole, VisualVM • ThreadMXBean • jstack (-F) • Consecutive thread dumps • Stop motion animation

  7. Hung or Slow App • Long GC pauses and/or high GC overhead • Basic GC tuning • max heap size: -Xmx • type of collector used • -XX:+UserSerialGC • -XX:+UseParallelGC/-XX:+UseParallelOldGC • -XX:+UseConcMarkSweepGC • -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC (jdk6u14+) • Advanced GC tuning • young generation size: -Xmn • Baseline, tune, measure one change at a time • Demo: HPjmeter – garbage collection analysis (and more…)

  8. Hung or Slow App • Deadlock • Take thread dump to run the JVM’s deadlock detector • Looping Threads • Monitor CPU times of running threads • ThreadMXBean • JTop plug-in for JConsole/VisualVM • Inspect stack trace of suspicious threads Source: TBD

  9. Slow or Hung App • Blocked threads • Look for blocked threads waiting on the same condition • Identify bottleneck for resource contention • Inspect code for incautious and/or improper synchronization • Demo: samurai – thread dump analysis tool • Stuck threads • Look for runnable threads with the same stack trace across consecutive thread dumps • Some common causes: • Blocking for a network call without specifying connect and/or read timeout (default may be no timeout) • Long execution time for calls to backend servers

  10. Links • Presentation http://www.apache.org/~billa/javaone2011 • HPjmeterhttps://h20392.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=HPJMETER • samurai http://yusuke.homeip.net/samurai/en/index.html

More Related