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Monitoring a WebLogic Server Domain

The following sections explain how to monitor your WebLogic Server domain:

- Overview of Monitoring

- Monitoring Servers

- Monitoring JDBC Connection Pools

Overview of Monitoring

The tool for monitoring the health and performance of your WebLogic Server domain is the Administration Console. The Administration Console allows you to view status and statistics for WebLogic Server resources such as servers, HTTP, the JTA subsystem, JNDI, security, CORBA connection pools, EJB, JDBC, and JMS.

Monitoring information is presented in the right pane of the Administration Console. You access a page by selecting a container or subsystem, or a particular entity under a container, on the hierarchical domain tree, in the left pane.

The Administration Console provides three types of page that contain monitoring information:

- Monitoring tab pages for a particular entity (such as an instance of a JDBC Connection Pool or a particular server's performance)

- Tables of data about all entities of a particular type (such as the WebLogic Servers table)

- Views of the domain log and of the local server logs. For information about log messages, see Using Log Messages to Manage WebLogic Servers.

The Administration Console obtains information about domain resources from the Administration Server. The Administration Server, in turn, is populated with Management Beans (MBeans), based on Sun's Java Management Extension (JMX) standard, which provides the scheme for management access to domain resources.

The Administration Server contains both configuration MBeans, which control the domain's configuration, and run-time MBeans. Run-time MBeans provide a snapshot of information about domain resources, such as JVM memory usage or the status of WebLogic Servers. When a particular resource in the domain (such as a Web application) is instantiated, an MBean instance is created which collects information about that particular resource.

When you access a monitoring page for particular resources in the Administration Console, the Administration Server performs a GET operation to retrieve the current attribute values.

The following sections describe some of the monitoring pages that are useful for managing a WebLogic Server domain. These pages have been selected simply to illustrate the facilities provided by the Administration Console.

Monitoring Servers

The servers table and the monitoring tab pages for individual servers enable you to monitor WebLogic Servers. The servers table provides a summary of the status of all servers in your domain. If only a small subset of the log messages from the server are forwarded to the domain log, accessing the local server log may be useful for troubleshooting or researching events.

For more information about the log files and the logging subsystem, see Using Log Messages to Manage WebLogic Servers.

You can access monitoring data for each WebLogic server from the monitoring tabs for that server. The Logging tab provides access to the local log for the server (that is, the log on the machine where the server is running).

The Monitoring—>General tab page indicates the current status and provides access to the Active Queues table, the Active Sockets table, and the Connections table. The Active Execute Queues table provides performance information such as the oldest pending request and the queue throughput.

Performance

The Monitoring—>Performance tab graphs real-time data on JVM memory heap usage and request throughput. This tab page also enables you to force the JVM to perform garbage collection on the memory heap.

The Java heap is a repository for Java objects (live and dead). Normally you do not need to perform garbage collection manually because the JVM does this automatically. When the JVM begins to run out of memory, it halts all execution and uses a garbage collection algorithm to free up space no longer used by Java applications.

On the other hand, developers debugging applications may have occasion to force garbage collection manually. Manual garbage collection may be useful, for example, if they are testing for memory leaks that rapidly consume JVM memory.

Server Security

The Monitoring—>Security tab provides statistics about invalid login attempts and locked and unlocked users.

JMS

The Monitoring—>JMS tab provides statistics on JMS servers and connections. This page also provides links to the tables of active JMS connections and active JMS servers, which monitor such attributes as total current sessions.

JTA

The Monitoring—>JTA tab provides statistics on the Java Transactions subsystem such as total transactions and total rollbacks. The page provides links to tables that list transactions by resource and name, and a table of in-flight transactions.

Monitoring JDBC Connection Pools

Java Database Connectivity (JDBC) subsystem resources can also be monitored via the Administration Console. The Monitoring tab for a JDBC connection pool allows you to access a table listing statistics for the instances of that pool. As with other entity tables in the Administration Console, you can customize the table to select which attributes you want to be displayed.

A number of these attributes provide important information for managing client database access.

The Waiters High field indicates the highest number of clients waiting for a connection at one time. The Waiters field tells you how many clients are currently waiting for a connection. The Connections High field indicates the highest number of connections that have occurred at one time. The Wait Seconds High field tells you the longest duration a client has had to wait for a database connection. These attributes allow you to gauge the effectiveness of the current configuration is in responding to client requests.

If the Connections High field value is close to the value of the Maximum Capacity field (set on the Configuration Connections tab), you might consider increasing the value of Maximum Capacity (the maximum number of concurrent connections). If the value in the Waiters High field indicates that clients are subject to a long wait for database access, then you might want to increase the size of the pool.

The value in the Shrink Period field is the length of time the JDBC subsystem waits before shrinking the pool from the maximum. When the subsystem shrinks the pool, database connections are destroyed. Creating a database connection consumes resources and can be time-consuming. If your system has intermittent bursts of client requests, a short shrink period might mean that database connections are being recreated continually, which may degrade performance.

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