JMX
For Monitoring and Maintenance
JA-SIG - December 4, 2005 – Atlanta, GA
Eric Dalquist
Division of Information Technology
University of Wisconsin – Madison
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The Problem
How to monitor and manage JVMs?
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Heap usage
Threads
Connection pools
Simultaneous users
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Current Solutions
• Garbage collector logs
– Not the easiest to read
– Need to have a session open to each machine
• Custom monitoring code
– Can’t always access interesting information
– Code you have to maintain and modify
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The JMX Solution
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Java Management eXtensions
Open standard (JSR-160)
API and tools included with Java 5
Provides both Monitoring and Management
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Advantages of JMX
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Standards based means little or no coding
Many applications already instrumented
Existing tools to connect to MBean servers
Frameworks to assist in instrumentation
Very little impact on server performance
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Instrumentation
• MBeans – Management beans
– JavaBean style objects
– Provide information
• Statistics, current state, overall summary
– Provide notifications
• Application events, values out of bounds
– Provide management
• Live configuration changes
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Instrumentation
• MBean Server
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MBeans are registered with the server
Management tools connect to the server
Aggregates information for tools
Polls MBeans and manages data
Manages MBean access rights
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Monitoring & Management
• JMX Client
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Can view all exposed MBeans and properties
Monitor multiple MBean servers (JVMs)
Subscribe to MBean event notifications
Modify writeable MBean properties
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JMX Clients
• JConsole
– Comes with Java 5 and later
– Swing based desktop application
• MC4J
– Open source Swing based desktop application
– Remembers server configuration
– Custom monitoring panel capabilities
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JMX Clients
• JManage
– Web based application
• Multiple users can monitor JVMs
– Can connect to multiple JVMs
• Organize JVMs into clusters
– 2.0 beta recently released
• Roadmap includes logging data to a database
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JConsole
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MC4J
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jManage
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JMX @ UW-Madison
• Metrics gathering for performance tuning
– Monitor heap usage and GC activity
– Tune caches & resource pools during tests
• Monitoring production servers
– Watch for anomalies
– Gather usage statistics
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Performance Testing
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JMX adds another view of JVM metrics
Heap usage for all three heap spaces
Resource pool usage
Cache performance and ratios
Thread pool usage and sizing information
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JVM Summary
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Old Gen Heap
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Production Monitoring
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JConsole & MC4J are used
Heap usage for memory leaks
Thread pools & session counts for capacity
Connection pools for database health
Time spent doing garbage collection
Portlet output caches & query statistics
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Tomcat Thread Pool
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Portal Session Count
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How To Instrument
• Spring MBean exporter
– Easiest way to expose JavaBeans
– Only need to declare beans to be exposed
– Limited in exported bean configuration
• JDK MBean APIs
– Powerful API for describing data to export
– Non-trivial coding required
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JMX & JA-SIG
• uPortal 3 Beans
– Using Spring MBean exporter
– Access to caches, thread pools, Hibernate stats
• Spring based portlets
– Export caching, statistics and usage data
– Bookmarks Portlet
– XSLT Portlet
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uPortal 3 RC1 Beans
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Bookmarks Portlet
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XSLT Portlet
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