Servlet Sessions attributes
The Servlet Sessions attribute group provides information about servlet sessions.
A session is a series of requests to a servlet, originating from the same user at the same browser. Applications running in a Web container use Sessions to monitor the actions of individual users. The attributes within this group are used to build the Sessions workspace. The Servlet Sessions attribute group provides information about servlet sessions.
- The attributes within this attribute group contain zeros for performance data if your site has set configuration value Resource Data Collection Method to On Demand (for on-demand sampling) and if you have not yet run applications that generate performance data. To report performance data in these attributes after installing and configuring the data collector, use the WebSphere® administrative console to set the appropriate PMI instrumentation level.
- The monitoring agent is set by default to provide on-demand sampling; thus the attributes within this attribute group initially contain zeros until you select the workspace and select it again later. Each time you select the workspace, these attributes are updated with the latest data.
Average Concurrently Active Sessions The average number of concurrently active sessions during the sampling interval. A session is active if WebSphere Application Server is currently processing a request that uses the session. The valid format is a decimal (formatted to three decimal places). This value is an average of several values collected over an interval. The interval can be either between this time and the previous time you activated this workspace, or fixed (normally 60 seconds), depending on the configuration of the monitoring agent.
Average Concurrently Live Sessions The average number of sessions cached in memory during the sampling interval. The valid format is a decimal (formatted to three decimal places). This value is an average of several values collected over an interval. The interval can be either between this time and the previous time you activated this workspace, or fixed (normally 60 seconds), depending on the configuration of the monitoring agent.
Average Serializable Session Object Size (bytes) The average size (in bytes) of the serializable attributes of in-memory sessions. This number is at a session level only and includes only session objects that contain at least one serializable attribute object (a session can contain some attributes that are serializable and some that are not). This value is a measurement of the data at the end of the PMI sampling interval, not of the data in the entire sampling interval. The valid format is a positive integer.
Average Session Lifetime (ms) The average session lifetime (in milliseconds), calculated by subtracting the time the session was created from the time it was invalidated. The valid format is a decimal (formatted to three decimal places).
Session Lifetime Count The count of times that were averaged for Average Session Lifetime . The valid format is a 4-byte integer. If the number is too big to be stored, a value of -2 is used.
Broken Session Affinities The number of HTTP session affinities that broke, not counting WebSphere application server intentional breaks of session affinity. This is the number of requests received for sessions that were last accessed from another web application and can indicate failover processing or a corrupted plug-in configuration. The valid format is a positive integer.
Broken Session Affinity Rate (per sec) The rate (per second) of the number of HTTP session affinities that break, not counting the WebSphere application server intentional breaks of session affinity, during the sampling interval. The valid format is a decimal (formatted to three decimal places).
Cache Discard Rate (per sec) The rate (per second) at which session objects have been forced out of the cache during the sampling interval. The valid format is a decimal (formatted to three decimal places).
Cache Discards The number of session objects that have been forced out of the cache. An LRU algorithm removes old entries to make room for new sessions and cache misses (this applies only to persistent sessions). The valid format is a positive integer.
Enterprise Application Name The name of the Enterprise application running the servlet. The valid format is an alphanumeric string, with a maximum of 256 characters.
External Read Size (bytes) The size (in bytes) of the session data read from the persistent store (applicable only to serialized, persistent sessions). The valid format is a decimal (formatted to three decimal places).
External Read Time (ms) The time (in milliseconds) taken to read the session data from the persistent store (applicable only to persistent sessions). For multirow sessions, the metrics are for the attributes; for single-row sessions, the metrics are for the whole session. When using a JMS persistent store, the user has the choice of whether to serialize the data being replicated; if the data are not serialized, this counter is not available. The valid format is a decimal (formatted to three decimal places).
External Write Size (bytes) The size (in bytes) of session data written to the persistent store (applicable only to serialized, persistent sessions). The valid format is a decimal (formatted to three decimal places).
External Write Time (ms) The time (in milliseconds) taken to write the session data from the persistent store (applicable only to serialized, persistent sessions). The valid format is a decimal (formatted to three decimal places).
Failed Session Request Rate (per sec) The rate (per second) that a request for a new session could not be handled because it would exceed the maximum session count for the sampling interval. The valid format is a decimal (formatted to three decimal places).
Failed Session Requests This attribute collects data from the NoRoomForNewSessionCount metric in the Servlet Sessions Counters PMI module. The number of times a request for a new session could not be handled because it would exceed the maximum session count; this applies only to a session in memory with AllowOverflow=false. The valid format is a positive integer.
Instrumentation Level The web instrumentation level for this web application. For WebSphere Version 5, the valid values are None, Low, Medium, High, and Maximum; for WebSphere Version 6 or later, the valid values are None, Basic, Extended, All, Custom. Blank if no instrumentation level is set.
Interval (sec) The length (in seconds) of the sampling interval. The valid format is a positive integer.
Max Serializable Session Object Size (bytes) The maximum size (in bytes) of the serializable attributes of in-memory sessions. This number is at a session level only and includes only session objects that contain at least one serializable attribute object (a session can contain some attributes that are serializable and some that are not). This value is a measurement of the data at the end of the PMI sampling interval, not of the data in the entire sampling interval. The valid format is a positive integer.
Min Serializable Session Object Size (bytes) The minimum size (in bytes) of the serializable attributes of in-memory sessions. This number is at a session level and includes only session objects that contain at least one serializable attribute object (a session can contain some attributes that are serializable and some that are not). This value is a measurement of the data at the end of the PMI sampling interval, not of the data in the entire sampling interval. The valid format is a positive integer.
Node Name The name of the system on which the server is running. The valid format is an alphanumeric string, with a maximum of 128 characters.
Nonexistent Session Request Rate (per sec) The rate (per second) of requests for a session that no longer exists (presumably because the session timed out) during the sampling interval. The valid format is a decimal (formatted to three decimal places).
Nonexistent Session Requests The number of requests for a session that no longer exists (presumably because the session timed out). Use this counter to determine if the timeout is too short. The valid format is a positive integer.
Origin Node The name of the server subnode. The valid format is an alphanumeric string, with a maximum of 128 characters.
Sample Date and Time The date and time the monitoring agent collected the data. The valid format is a 12-character timestamp. For the STR and SCAN functions, the format is MM/DD/YY HH:MM:SS; the following table shows the values contained in this character string.
| Character String | Meaning |
|---|---|
| MM | Month |
| DD | Day |
| YY | Year |
| HH | Hour |
| MM | Minute |
| SS | Second |
Example: 09/13/06 18:32:03 indicates the data was collected on September 13 2006, at 18:32:03.
This attribute was designed for logging and reporting data-collection times rather than for creating situations. To specify a time and date for comparison and testing, use attributes from the Universal Time or Local Time groups.
Server Name The name of the WebSphere Application Server. The valid format is an alphanumeric string, with a maximum of 256 characters.
Session Creation Rate (per sec) The rate (per second) of sessions created during the sampling interval. The valid format is a decimal (formatted to three decimal places).
Session Invalidation Rate (per sec) The rate (per second) at which sessions were invalidated during the sampling interval. The valid format is a decimal (formatted to three decimal places).
Sessions Created The number of sessions created during the sampling interval. The valid format is a positive integer.
Sessions Invalidated The number of sessions invalidated during the sampling interval. The valid format is a positive integer.
Set Instrumentation Level Type Indicates the WebSphere resource category, which is used by the agent to modify the Instrumentation Level for transaction data collection.
Summary of Servlet Sessions Whether this row is a summary row of statistical totals collected for the servlet sessions. The valid values are No and Yes.
Time since Last Activated The time difference (in the locale-specific format, for example hh:mm:ss.msecs) between the previous and current access timestamps. Does not include session timeouts. The valid format is a timestamp.
Total Serializable Session Object Size (bytes) The total size (in bytes) of all the in-memory session objects. This includes only the serializable attributes in the session object; at least one such attribute must be present to be included in this total. This value is a measurement of the data at the end of the PMI sampling interval, not of the data in the entire sampling interval. The valid format is a positive integer.
Serializable Session Object Size Count The count of object sizes that were used for Total Serializable Session Object Size. The valid format is a 4-byte integer. If the number is too big to be stored, a value of -2 is used.
Web Application Archive The name of the web application WAR file. The valid format is an alphanumeric string, with a maximum of 128 characters.