要約

This page provides a way of collecting Thread dumps (a breakdown of what every thread is doing for a Java process) and the output of top for Lunix/Unix operating systems (shows what each native OS thread is consuming as far as resources are concerned). This breakdown could normally be collected with something like jProfiler as per Use jProfiler to analyse Jira application performance - in this example we're using native (free) tools to collect information.

You may capture Thread dumps whenever Jira is taking longer than expected to process requests or taking up more machine resources than expected.

環境

Any version of Jira Software or Jira Service Management, Server or Data Center.

ソリューション

If running Jira on a container, skip to the Steps for Atlassian Docker containers below.

1. Optional: Enable Thread diagnostics in Administration > System > Troubleshooting and Support Tools. This will provide additional details on the Tomcat threads (namely the URI and username) and will allow for faster troubleshooting.

   1. This is preferred, but if your system is currently in a bad state, please skip step 1 and proceed forward to generate thread dumps.
   2. In earlier versions, you might not see the Thread diagnostics tab. This feature was introduced with Atlassian Troubleshooting and Support Tools version 1.32.3 (bundled plugin). You may upgrade this plugin or use Thready plugin instead.

2. Download and install the scripts located in https://bitbucket.org/atlassianlabs/atlassian-support/downloads/ or run the commands in the Workaround section below.

3. Execute the scripts during periods of slowness or unresponsiveness and provide the resulting tar.gz file to support.
4. Select 'Y' to thread dumps. The 'N' option is for heap dump.
5. Optional: Run the disk speed tests with the same scripts, which are covered in more detail in our Testing Disk Access Speed KB.

To analyze them:

• Look in the resulting CPU usage files to identify which threads are consistently using a lot of CPU time.

• Use a tool such as TDA and check the native ID to correspond it to the thread dump.
• Review the stack traces and search for known bugs on jira.atlassian.com.

回避策

How to manually run the tools, requires Java Development Kit (JDK)

• Identify the JIRA application PID by using a command such as:
  Linux/Unix:

  JIRA_PID=`ps aux | grep -i jira | grep -i java | grep -v grep | awk  -F '[ ]*' '{print $2}'`;

  Windows の場合:

  $JIRA_PID = (Get-Process -name "tomcat8.exe.x64").id

  Alternatively, you can use the following command to identify the process ID of JIRA when it is currently running:

  
  

  JIRA_PID=$(cat <JIRA_INSTALL>/work/catalina.pid)

• Then run the following command - it generates 6 snapshots of CPU usage and thread dumps with 10 seconds interval for a minute.

  Linux (tested with Ubuntu / Debian):

  for i in $(seq 6); do top -b -H -p $JIRA_PID -n 1 > jira_cpu_usage.`hostname`.`date +%s`.txt; jstack -l $JIRA_PID > jira_threads.`hostname`.`date +%s`.txt; sleep 10; done

  Unix (tested with Solaris):

  for i in $(seq 6); do prstat -L -p $JIRA_PID -n 500 1 1 > jira_cpu_usage.`hostname`.`date +%Y-%m-%d_%H%M%S`.txt; jstack -l $JIRA_PID > jira_threads.`hostname`.`date +%Y-%m-%d_%H%M%S`.txt; sleep 10; done

  Windows (tested with PowerShell 5.1):

  1..6|foreach{jstack -l $JIRA_PID|Out-File -FilePath "app_threads.$(Get-Date -uformat %s).txt";sleep 10}

   Windows has no equivalent to the top command, so we can't get the thread CPU usage programmatically. For thread CPU usage, check Use Windows Process Explorer to troubleshoot Jira server Performance.
  
  

• Look in the resulting CPU usage files to identify which threads are consistently using a lot of CPU time.

• Use a tool such as TDA and check the native ID to correspond it to the thread dump.
• Alternatively, take the PID of the top 10 threads which are using CPU time and convert them to hexadecimal. Eg: 11159 becomes 0x2b97.
• Search up the Hex values in the thread dumps to figure out which threads are using up all the CPU.

Parsing Thread dumps from the catalina.out file (kill -3)

If you captured Thread dumps issuing the kill -3 command, the JVM will write them to stdout (Standard Output), which is usually the catalina.out file located in Jira's installation directory logs folder.

To extract the Thread dumps out of the file, you can run this example command below or a similar one (change the path at the end to where your copy of catalina.out file is):

awk '/^[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}$/{n++;td=1;lastLine=$0;outFile=("jira_threads." sprintf("%06d", n) ".txt")}; {if (td) {print $0 >> outFile; close(outFile)}}; /object space/{if (lastLine ~ /PSPermGen/) {td=0}}' tomcat-logs/catalina.out

It'll generate a txt file for every Thread dump identified in the logs:

$ ls -1 | head -20
jira_threads.000001.txt
jira_threads.000002.txt
jira_threads.000003.txt
jira_threads.000004.txt
jira_threads.000005.txt
jira_threads.000006.txt
jira_threads.000007.txt
jira_threads.000008.txt
jira_threads.000009.txt
jira_threads.000010.txt

If your catalina.out is too large, you should implement a rotation on it. (please refer to Configure log rotation for the catalina log in Jira Server for more on this)

You may also need to split the file before running the awk parsing command above so it doesn't take too long.

Atlassian Docker コンテナーのステップ

/opt/atlassian/support/thread-dumps.sh を docker exec を介して実行すると、スレッド ダンプの収集をコンテナー化されたアプリから簡単にトリガーできます。次に例を示します。

docker exec my_container /opt/atlassian/support/thread-dumps.sh

初期設定では、このスクリプトはスレッド ダンプ 10 個を 5 秒間隔で収集します。-c / --count と -i / --interval をそれぞれ使用することで、これはカウントと間隔のカスタム値を渡して上書きできます。たとえば、スレッド ダンプ 20 個を 3 秒間隔で収集するには、次のようにします。

docker exec my_container /opt/atlassian/support/thread-dumps.sh --count 20 --interval 3

Docker コンテナーを Kubernetes 環境で実行している場合は、次のようにコマンドを実行できます。

kubectl exec -it jira-1 -n jira -- bash -c "/opt/atlassian/support/thread-dumps.sh --count 20 --interval 3"

Replace -it jira-1  with the pod name, and -n jira  with the namespace where the Jira pods are running.

スレッド ダンプは $APP_HOME/thread_dumps/<date> に書き込まれます。

注: 初期設定では、このスクリプトは「スレッドモード」のトップ ランからの出力もキャプチャします。これは、-n / --no-top を渡すことで無効にできます。

The Troubleshooting section on https://hub.docker.com/r/atlassian/jira-software has additional information.