Enabling JMX counters for performance monitoring

JMX を使用して何を監視できますか?

It is possible to monitor various statistics using JMX counters within Stash. Below are some examples of some statistics that can be monitored.

Stash repository statistics

• プロジェクトの総数
• Total number of repositories
• Git pushes and pulls
• Various thread pools and attributes

Thread pools

Thread pool attributes

Ticket statistics

Stash uses 'tickets' as a mechanism for creating back-pressure to prevent the system from being overloaded with requests. There are two types of tickets used by stash, hosting tickets and command tickets. 
Hosting tickets: Limits the number of SCM hosting operations, meaning pushes and pulls over HTTP or SSH, which may be running concurrently. 
Command tickets:  Limits the number of SCM commands, such as: `git diff`, `git blame`, or `git rev-list`, which may be running concurrently.

Stash supports the following metrics for each ticket type.

Interesting 3rd party library attributes

Stash exposes the JMX attributes from number of third party libraries. Listed below is a sample of the attributes that are particularly interesting from an operations perspective. 

BoneCP  (com.jolbox.bonecp.BoneCP)

Hibernate (org.hibernate.com.stash.core.org.hibernate.stat.Statistics.org.hibernate.stat.internal.ConcurrentStatisticsImpl)

Expose JMX MBeans within Stash

To enable Stash to publish specific statistics using JMX you need to

1. Modify the stash-config.properties file.
2. Create a JMX password file for secure access to JMX monitoring.
3. Modify the setenv.sh file to enable Stash to expose JMX Mbeans.
   

These changes will not take effect until Stash has been restarted.

Modify the stash-config properties file

To modify (or create) the stash-config.properties file

1. Create the stash-config.properties file, in the shared folder of your Stash home directory. Take care to use the standard format for Java properties files.

   The stash-config.properties file is created automatically if you previously performed a database migration.

2. Add this property to the file.

   jmx.enabled=true

Set up the JMX password file

To set up a JMX password file to secure access to JMX monitoring

1. Create a file named jmx.access.

   This file will contain password information. Ensure the file is only readable by the secure user Stash will run under. However, note that if the Stash user cannot read the file Stash will fail to start.

2. Edit the jmx.access file to include this property and save the file.
   

   monitorRole=<password>

   If you wish to user a username other than monitorRole or controlRole you will need to modify the jmxremote.access file that is bundled with stash in the .install4j/jre.bundle/Contents/Home/jre/lib/management/ directory.

Modify the Stash environment file

To modify the setenv.sh (for Windows setenv.bat) files to enable JMX monitoring for Stash

1. Within the bin directory, locate the file setenv.sh (for Windows setenv.bat) and change these properties.

   JMX_REMOTE_AUTH=password
   JMX_REMOTE_PORT=3333
   RMI_SERVER_HOSTNAME=-Djava.rmi.server.hostname=<hostname>
   JMX_PASSWORD_FILE=<path>/jmx.access

2. Restart Stash.

Expose JMX MBeans when Stash is run as a Windows service

To expose JMX MBeans when Stash is run as a Windows service.

1. Stop the Stash service.

2. Open the command line prompt and enter.

   cmd

3. Navigate to the Stash bin directory.

   cd <Stash Installation dir>\bin

4. Run this command.

   tomcat8w //ES//AtlassianStash

5. In the window that appears, click on the Java tab to see the list of current startup options. Under "Java Options:" form, input the value

   -Dcom.sun.management.jmxremote.port=<JMX_REMOTE_PORT>   
   -Djava.rmi.server.hostname=<hostname>
   -Dcom.sun.management.jmxremote.ssl=false 
   -Dcom.sun.management.jmxremote.password.file=<JMX_PASSWORD_FILE> 

   Ensure the owner of this password file is the secure user Stash will run as. If the Stash user cannot read the file, Stash will fail to start.

6. Replace the values within the < > characters.

   JMX_REMOTE_PORT=3333
   JMX_PASSWORD_FILE=<path>\jmx.access

7. Restart Stash Service.

Verify JMX is configured correctly

These steps use JConsole to test that JMX has been configured correctly. JConsole is a utility that ships with the Oracle JDK.

1. To start the jconsole utility, from a command line prompt enter

   jconsole

   

2. Create a new JConsole connection with similar connection settings.

   stash	the hostname of the instance of Stash to monitor
   3333	the JMX port number previously configured.
   username, password	values configured within the JMX password file jmx.access.

3. Click Connect.

When configured correctly, you will see these properties.

Example performance dashboard

This dashboard was generated using Java Mission Control that ships with the Oracle JDK (since 1.7u40). See the documentation that comes with your JMX client of choice for more information. 

Configuring JMX to use SSL

You can find information about the options for configuring JMX to use SSL in the setenv files. Comprehensive documentation is available from Oracle.