Enable PMI data collection
Enable PMI data collection to diagnose problems and tune application performance.
Before you begin
Performance Monitoring Infrastructure (PMI) needs to be enabled (by default PMI is enabled) before collecting any performance data. PMI should be enabled before the server starts. If PMI is enabled after the server is started, the server needs to be restarted to start the PMI.
About this task
When PMI service is enabled, the monitoring of individual components can be enabled or disabled dynamically. PMI provides four predefined statistic sets that can be used to enable a set of statistics. The following table provides details about the statistic sets. If the predefined statistic sets does not meet your monitoring requirement, the Custom option can be used to selectively enable or disable individual statistics.
Statistic set Description None All statistics are disabled. Basic Statistics specified in J2EE 1.4, as well as top statistics like CPU usage and live HTTP sessions are enabled. This set is enabled out-of-the-box and provides basic performance data about runtime and application components. Extended Basic set plus key statistics from various WAS components like WLM and Dynamic caching are enabled. This set provides detailed performance data about various runtime and application components. All All statistics are enabled. Custom Enable or disable statistics selectively. Custom setting
WebSphere Application Server Version 6.0 introduces fine-grained control to enable/disable statistics individually. The fine-grained control is available under the custom statistic set.
Though the V5.x monitoring levels {N, L, M, H, X} are deprecated in Version 6.0 and above, the 5.x PMI APIs are supported for backward compatibility. It is possible to use a v6 or later API to set the monitoring level and a V5.0 API to get the monitoring level. A new level ‘F’ – “fine-grained” is introduced to indicate to the V5.x API that the fine-grained or V6.x monitoring specification is in effect. This new level ‘F’ will be returned if a V5.x API is used to get the monitoring level from a server using V6.x monitoring specification.
In WebSphere Application Server V4.0 and V5.0, the statistics were enabled based on a monitoring/instrumentation level. The levels are None, Low, Medium, High and Max {N, L, M, H, X}. Enabling at a given level will include all the statistics at the given level plus counters from levels below the given level. So if you enable the Web Application module at level Medium {M} it enables all the counters at level M, plus all the Low {L} level counters. See PMI data collection for more information.
Sequential Update
In order to minimize the monitoring overhead, the updates to CountStatistic, AverageStatistic, and TimeStatistic are not synchronized. Since these statistic types track total and average, the extra accuracy is generally not worth the performance cost. The RangeStatistic and BoundedRangeStatistic are very sensitive, therefore, they are always are synchronized. If needed, updates to all the statistic types can be synchronized by checking the Use sequential update check box.
Procedure
Enable PMI using one of the following methods:
- Enabling PMI using the administrative console
- Enabling PMI using the wsadmin tool
- Enabling the Java virtual machine profiler data
See also
Enabling PMI using the administrative console
Enabling PMI using the wsadmin tool
Enabling the Java virtual machine profiler data