Purpose

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 (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.

Symptoms

JIRA application is behaving slowly, and you need more information as to what part of it is being slow.

Solution

1. Optional: Install the Thready plugin, if it is supported by your JIRA version. This will provide additional details on the Tomcat threads (namely the URI) 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. Download and install the scripts located in https://bitbucket.org/atlassianlabs/atlassian-support/.

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.
   
   1. Select 'N' to 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.

Workaround

How to manually run the tools

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

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

  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.`date +%s`.txt; jstack -l $JIRA_PID > jira_threads.`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.`date +%Y-%m-%d_%H%M%S`.txt; jstack -l $JIRA_PID > jira_threads.`date +%Y-%m-%d_%H%M%S`.txt; sleep 10; done

• Look in the resultingcpuusage 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.

Steps for Atlassian docker containers

/opt/atlassian/support/thread-dumps.sh can be run via docker exec to easily trigger the collection of thread dumps from the containerized application. For example:

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

By default this script will collect 10 thread dumps at 5 second intervals. This can be overridden by passing a custom value for the count and interval, by using -c / --count and -i / --interval respectively. For example, to collect 20 thread dumps at 3 second intervals:

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

Thread dumps will be written to $APP_HOME/thread_dumps/<date>.

Note: By default this script will also capture output from top run in 'Thread-mode'. This can be disabled by passing -n / --no-top

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