Performance data organization
Performance Monitoring Infrastructure (PMI) provides server-side monitoring and a client-side API to retrieve performance data. PMI maintains statistical data within the entire WAS domain, including multiple nodes and servers. Each node can contain one or more appservers. Each server organizes PMI data into modules and submodules.
The Tivoli Performance Viewer organizes performance data in a centralized hierarchy of the following objects:
Node A node represents a physical machine in the WAS administrative domain. Server A server is a functional unit that provides services to clients over a network. No performance data is collected for the server itself. Module A module represents one of the resource categories for which collected data is reported to the performance viewer. Each module has a configuration file in XML format. This file determines organization and lists a unique identifier for each performance data in the module. Modules include: Submodule A submodule represents a fine granularity of a resource category under the module. For example, ORB thread pool is a submodule of the thread pool category. Submodules can contain other submodules. Counter A counter is a data type used to hold performance information for analysis. Each resource category (module) has an associated set of counters. The data points within a module are queried and distinguished by the MBean ObjectNames or PerfDescriptors. Examples of counters include the number of active enterprise beans, the time spent responding to a servlet request and the number of kilobytes of available memory.
The Tivoli Performance Viewer allows users to view and manipulate the data for counters. A particular counter type can appear in several modules. For example, both the servlet and enterprise bean modules have a response time counter. In addition, a counter type can have multiple instances within a module. For example, in the figure above, both the Enterprise beans module and Bean1 have an Avg Method RT counter.
Counters are enabled at the module level and can be enabled or disabled for elements within the module. For example, in the figure, if the enterprise beans module is enabled, its Avg Method RT counter is enabled by default. However, you can then disable the Avg Method RT counter even when the rest of the module counters are enabled. You can also, if desired, disable the Avg Method RT counter for Bean1, but the aggregate response time reported for the whole module no longer includes Bean1 data.
Each counter has a specified monitoring level: none, low, medium, high or maximum. If the module is set to lower monitoring level than required by a particular counter, that counter is not enabled. Thus, if Bean1 has a medium monitoring level, Gets Found and Num Destroys are enabled because they require a low monitoring level. However, Avg Method RT is not enabled because it requires a high monitoring level.
Data collection can affect performance of the appserver. The impact depends on the number of counters enabled, the type of counters enabled and the monitoring level set for the counters.
The following PMI modules are available to provide statistical data...
Enterprise bean modules Data counters for this category report load values, response times, and life cycle activities for enterprise beans. Examples include the average number of active beans and the number of times bean data is loaded or written to the database. Information is provided for enterprise bean methods and the remote interfaces used by an enterprise bean. Examples include the number of times a method is called and the average response time for the method. In addition, the Tivoli Performance Viewer reports information on the size and use of a bean objects cache or enterprise bean object pool. Examples include the number of calls attempting to retrieve an object from a pool and the number of times an object is found available in the pool.
JDBC connection pools Data counters for this category contain usage information about connection pools for a database. Examples include the average size of the connection pool or number of connections, the average number of threads waiting for a connection, the average wait time in milliseconds for a connection, and the average time the connection is in use.
J2C connection pools Data counters for this category contain usage information about the Java 2 Platform Enterprise Edition (J2EE) Connector architecture that enables enterprise beans to connect and interact with procedural back-end systems, such as Customer Information Control System (CICS), and Information Management System (IMS). Examples include the number of managed connections or physical connections and the total number of connections or connection handles.
Java Virtual Machine API (JVM) Data counters for this category contain memory used by a process as reported by JVM run time. Examples are the total memory available and the amount of free memory for the JVM. JVM run time also includes data from the Java Machine Profiler Interface (JVMPI). This data provides detailed information about the JVM running the appserver.
Servlet session manager Data counters for this category contain usage information for HTTP sessions. Examples include the total number of accessed sessions, the average amount of time it takes for a session to perform a request, and the average number of concurrently active HTTP sessions.
Thread pools Data counters for this category contain information about the thread pools for ORB threads and the Web container pools used to process HTTP requests. Examples include the number of threads created and destroyed, the maximum number of pooled threads allowed, and the average number of active threads in the pool.
Java Transaction API (JTA) Data counters for this category contain performance information for the transaction manager. Examples include the average number of active transactions, the average duration of transactions, and the average number of methods per transaction.
Webapplications, servlet Data counters for this category contain information for the selected server. Examples include the number of loaded servlets, the average response time for completed requests, and the number of requests for the servlet.
Object Request Broker Data counters for this category contain information for the ORB. Examples include the object reference lookup time, the total number of requests, and the processing time for each interceptor.
Web Services Gateway (WSGW) Data counters for this category contain information for WSGW. Examples include the number of synchronous and asynchronous requests and responses.
System data Data counters for this category contain information for a machine (node). Examples include the CPU utilization and memory usage. Note that this category is available at node level, which means it is only available at NodeAgent in the multiple servers version.
Workload Management (WLM) Data counters for this category contain information for workload management. Examples include the number of requests, the number of updates and average response time.
Dynamic cache Data counters for this category contain information for the dynamic cache service. Examples include in-memory cache size, the number of invalidations, and the number of hits and misses.
Web services Data counters for this category contain information for the Web services. Examples include the number of loaded Web services, the number of requests delivered and processed, the request response time, and the average size of requests. You can access PMI data through the getStatsObject and the getStatsArray method in the PerfMBean. You need to pass the MBean ObjectName(s) to the PerfMBean.
Use the following MBean types to get PMI data in the related categories...
DynaCache dynamic cache PMI data EJBModule * Enterprise Java Bean (EJB) module PMI data (BeanModule) EntityBean * specific EJB PMI data (BeanModule) JDBCProvider * JDBC connection pool PMI data J2CResourceAdapter * J2C connection pool PMI data JVM JVM PMI data MessageDrivenBean * specific EJB PMI data (BeanModule) ORB Object Request Broker PMI data Server PMI data in the whole server, pass recursive=true to PerfMBean SessionManager * HTTP Sessions PMI data StatefulSessionBean * specific EJB PMI data (BeanModule) StatelessSessionBean * specific EJB PMI data (BeanModule) SystemMetrics system level PMI data ThreadPool * thread pool PMI data TransactionService JTA Transaction PMI data WebModule * web application (.war) PMI data Servlet * servlet PMI data WLMAppServer Workload Management PMI data WebServicesService Web services PMI data WSGW * Web services gateway PMI data To use the AdminClient API to query the MBean ObjectName for each MBean type. You can either query all the MBeans and then match the MBean type or use the query String for the type only: String query = "WebSphere:type=mytype,node=node,server=myserver,*";
Set the mytype, node, and myserver values accordingly. You get a Set value when you call the AdminClient class to query MBean ObjectNames. This response means that you can get multiple ObjectNames.
MBean types with a star (*) mean that there can be multiple ObjectNames in a server for the same MBean type. In this case, the ObjectNames can be identified by both type and name (but mbeanIdentifier is the real UID for MBeans). However, the MBean names are not predefined. They are decided at run time based on the applications and resources. When you get multiple ObjectNames, you can construct an array of ObjectNames that you are interested in. Then you can pass the ObjectNames to PerfMBean to get PMI data. You have the recursive and non-recursive options. The recursive option returns Stats and sub-stats objects in a tree structure while the non-recursive option returns a Stats object for that MBean only. More programming information can be found in "Develop your own monitoring applications".
See Also
Monitoring performance