Servlet session counters

Data counters for this category contain usage information for HTTP sessions.

Note: With the instrumentation level set to anything other than MAX, the values may be less accurate for TimeStatistics and CountStatistics (and in the case of CountStatistics, such as numConnectionHandles, can even be negative). This is due to counters not being synchronized. Synchronizing counters is very expensive in terms of resources, so it is only done when the instrumentation level is set to MAX.

Counter definitions
Name Key Description Version Granularity Type Level
Created sessions servletSessionsModule.createdSessions The number of sessions that were created 3.5.5 and later Per Web application CountStatistic Low
Invalidated sessions servletSessionsModule.invalidatedSessions The number of sessions that were invalidated 3.5.5 and later Per Web application CountStatistic Low
Session life time (ms) servletSessionsModule.sessionLifeTime The average session life time in milliseconds (time invalidated - time created) 3.5.5 and later Per Web application TimeStatistic Medium
Active sessions servletSessionsModule.activeSessions The number of concurrently active sessions. A session is active if the WebSphere Application Server is currently processing a request that uses that session. 3.5.5 and later Per Web application RangeStatistic High
Live sessions servletSessionsModule.liveSessions The number of local sessions that are currently cached in memory 5.0 and later Per Web application RangeStatistic High
No room for new sessions servletSessionsModule.noRoomForNewSession Applies only to session in memory with AllowOverflow=false. The number of times that a request for a new session cannot be handled because it exceeds the maximum session count. 5.0 Per Web application CountStatistic Low
Cache discards servletSessionsModule.cacheDiscards The number of session objects that have been forced out of the cache. A least recently used (LRU) algorithm removes old entries to make room for new sessions and cache misses. Applicable only for persistent sessions. 5.0 Per Web application CountStatistic Low
External read time servletSessionsModule.externalReadTime The time (milliseconds) taken in reading the session data from the persistent store. For multirow sessions, the metrics are for the attribute; for single row sessions, the metrics are for the entire session. Applicable only for persistent sessions. When using a JMS persistent store, you can choose to serialize the replicated data. If you choose not to serialize the data, the counter is not available. 5.0 Per Web application TimeStatistic Medium
External read size servletSessionsModule.externalReadSize Size of the session data read from persistent store. Applicable only for (serialized) persistent sessions; similar to external Read Time. 5.0 Per Web application TimeStatistic Medium
External write time servletSessionsModule.externalWriteTime The time (milliseconds) taken to write the session data from the persistent store. Applicable only for (serialized) persistent sessions. Similar to external Read Time. 5.0 Per Web application TimeStatistic Medium
External write size servletSessionsModule.externalWriteSize The size of the session data written to persistent store. Applicable only for (serialized) persistent sessions. Similar to external Read Time. 5.0 Per Web application TimeStatistic Medium
Affinity breaks servletSessionsModule.affinityBreaks The number of requests that are received for sessions that were last accessed from another Web application. This value can indicate failover processing or a corrupt plug-in configuration. 5.0 Per Web application CountStatistic Low
Session object size servletSessionsModule.serializableSessObjSize The size in bytes of (the serializable attributes of ) in-memory sessions. Only session objects that contain at least one serializable attribute object is counted. A session can contain some attributes that are serializable and some that are not. The size in bytes is at a session level. 5.0 Per Web application TimeStatistic Max
Time since last activated servletSessionsModule.timeSinceLastActivated The time difference in milliseconds between previous and current access time stamps. Does not include session time out. 5.0 Per Web application TimeStatistic Medium
Invalidated via timeout servletSessionsModule.invalidatedViaTimeout The number of sessions that are invalidated by timeout. 5.0 Per Web application CountStatistic Low
Activate non-exist sessions servletSessionsModule.activateNonExistSessions The number of requests for a session that no longer exists, presumably because the session timed out. Use this counter to help determine if the timeout is too short. 5.0 Per Web application CountStatistic Low



Related reference
Performance data organization



Searchable topic ID:   rprf_datacounter6
Last updated: Jun 21, 2007 4:55:42 PM CDT    WebSphere Application Server Network Deployment, Version 5.0.2
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