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EclipseLink supports a profiling and monitoring API through its SessionProfiler interface. This interface gives events that allows a profiler or monitoring service to record performance or metrics on the EclipseLink application.

As of EclipseLink 2.2 a PerformanceMonitor is provided to collect performance an metric information. When enabled the PerformanceMonitor will log the monitoring information at set intervals to the session log, allowing an application's performance to be analyzed.

Previous to EclipseLink 2.2, a PerformanceProfiler was provided, but it did not make use of the complete SessionProfiler API, and was only useful for profiling a single use case, not a multi-user server. A QueryMonitor was also provided that provided simple monitoring information on queries, but no detailed information.

The PerformanceMonitor is enabled through the "eclipselink.profiler" persistence unit property in the persistence.xml file.

Persistence unit property

<property name="eclipselink.profiler" value="PerformanceMonitor"/>

The PerformanceMonitor metrics can also be accessed through the API instead of dumping to the log.

For example:

Integer cacheHits = (Integer)((PerformanceMonitor)session.getProfiler()).getOperationTimings().get(SessionProfiler.CacheHits);

To disable the monitor logging set the dump time to a large value.

Integer cacheHits = (Integer)((PerformanceMonitor)session.getProfiler()).setDumpTime(Integer.MAX_VALUE);

Monitoring Levels

The profile weight can be configured for the PerformanceMonitor through the API. The default weight if the PerformanceMonitor is set is ALL. By default no profiler is set for a persistence unit, so no profiling or monitoring is done. The higher the level of monitoring the larger the performance overhead of the monitor.

Level Description
NONE No monitoring is done.
NORMAL Metrics are tracked, but profiling is not done.
HEAVY Metrics and profiling times are tracked.
ALL Metrics and profiling times are tracked.

Example Output

The PerformanceMonitor displays three types of information, counters, info, and timers.

A counter count the occurrence of an operation, such a a query, or cache hit.

An info records some static information, such as the time a session was connected, or the session's name.

A timer accumulates the total amount of time (in nano seconds) that a particular operation or query type took.

Performance Monitor:1279113281664
Operation	Value (ns)
Counter:CacheHits	1,375,664
Counter:CacheMisses	327
Counter:ClientSessionCreates	1,204,817
Counter:ConnectCalls	2
Counter:DataModifyQuery	48
Counter:DataModifyQuery:inventory	21
Counter:DataModifyQuery:order	27
Counter:DeleteObjectQuery	67,792
Counter:DeleteObjectQuery:Customer	1
Counter:ReadAllQuery	1,041,767.
Counter:ReadAllQuery:Item.findByCategory	733,827
Counter:ReadAllQuery:Item.findByCategory:CacheHits	733,779
Counter:ReadAllQuery:Item.findByCategory:CacheMisses	50
Counter:ReadObjectQuery	1,058,273
Counter:ReadObjectQuery:Item:item	130,063
Counter:ReadObjectQuery:Item:item:CacheHits	130,063
Counter:ReadObjectQuery:Item:item:CacheMisses	1
Counter:UnitOfWorkCommits	72,568
Counter:UnitOfWorkCreates	471,491
Counter:UnitOfWorkRollbacks	1
Counter:UpdateObjectQuery	71,498
Counter:UpdateObjectQuery:Customer	62,531
Info:LoginTime	Wed Jul 14 08:55:41 EDT 2010
Info:SessionName	file:/scratch/user_domains/servers/mt-1/app.jar
Timer:Caching	6,411,372,000
Timer:ConnectionManagement	17,225,641,000
Timer:DeleteObjectQuery	41,351,430,000
Timer:DeleteObjectQuery:Customer	4,441,000
Timer:DeleteObjectQuery:Customer:QueryPreparation	86,000
Timer:DeleteObjectQuery:Customer:SqlGeneration	28,000
Timer:DeleteObjectQuery:Customer:SqlPrepare	72,000
Timer:DeleteObjectQuery:Customer:StatementExecute	2,265,000
Timer:InsertObjectQuery	69,111,086,000
Timer:Logging	4,236,000
Timer:Merge	1,144,400,000
Timer:ObjectBuilding	31,914,397,000
Timer:QueryPreparation	984,396,000
Timer:ReadAllQuery	260,943,930,000
Timer:ReadAllQuery:Item:Item.findByCategory	14,790,333,000
Timer:ReadAllQuery:Item:Item.findByCategory:ObjectBuilding	250,959,000
Timer:ReadAllQuery:Item:Item.findByCategory:QueryPreparation	1,880,000
Timer:ReadAllQuery:Item:Item.findByCategory:RowFetch	113,552,000
Timer:ReadAllQuery:Item:Item.findByCategory:SqlGeneration	522,000
Timer:ReadAllQuery:Item:Item.findByCategory:SqlPrepare	2,055,000
Timer:ReadAllQuery:Item:Item.findByCategory:StatementExecute	107,382,000
Timer:Register	3,272,443,000
Timer:RowFetch	25,340,990,000
Timer:Sequencing	1,352,326,000
Timer:SqlGeneration	6,646,000
Timer:SqlPrepare	19,536,031,000
Timer:StatementExecute	508,589,220,000
Timer:TXAfterCompletion	1,854,152,000
Timer:TXBeforeCompletion	169,381,843,000
Timer:UnitOfWorkCommit	167,483,825,000
Timer:UpdateObjectQuery	46,440,589,000
Timer:UpdateObjectQuery:Customer	40,466,433,000
Timer:UpdateObjectQuery:Customer:QueryPreparation	867,496,000
Timer:UpdateObjectQuery:Customer:SqlGeneration	98,000
Timer:UpdateObjectQuery:Customer:SqlPrepare	1,319,333,000
Timer:UpdateObjectQuery:Customer:StatementExecute	32,901,366,000

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