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Garbage collection (GC) is a part of a Java application's JVM that automatically determines what memory a program is no longer using, and recycles it for other use. If the garbage collector does not reclaim enough memory, the heap will grow to accommodate more data. If heap growth is not controlled by efficient garbage collection, it can degrade the performance of the SAP Web Application server, and consequently, slowdown its operations. To keep tab on the garbage collection activity based on each type of garbage collection, you can use the SapWasGCTest.

For each type of garbage collection operation performed on the target SAP Web Application server, this test helps you gauge the garbage collection and identify the type of garbage collection that was performed to release maximum memory. When frequent performance dips are noticed on the target server, administrators can use this test to figure out if the dip in server performance is owing to excessive heap growth that was caused by inefficient garbage collection.

Outputs of the test : One set of results for each Process:Type of Garbage Collection triggered on the target SAP Netweaver Application Server being monitored.

Measurement	Description	Measurement Unit	Interpretation
numGC	Indicates the number of garbage collection operations of this type that occurred during the last measurement period.	Number	Compare the value of this measure across garbage collection types to identify the garbage collection type on which frequent garbage collection operations had occurred. The detailed diagnosis of this measure lists the reason for garbage collection, start time of GC, duration, CPU utilization, Object memory released, Object memory, class memory released, class memory , allocated heap memory and classes unloaded.
GCRate	Indicates the rate at which garbage collection operations of this type occurred.	Collections/min	A high value is indicative of frequent garbage collections. This could be owing to rapid and significant heap growth on the node. Frequent garbage collections on a node may degrade its performance. To avoid this, you may want to consider resizing the heap on that node.
durn	Indicates the time taken to perform a garbage collection operation of this type.	Milliseconds/collection	Ideally, the value of this measure should be low. This is because, the garbage collection (GC) activity tends to suspend the operations of the application until such time that GC ends. Longer the GC time, longer it would take for the application to resume its functions. To minimize the impact of GC on application performance, it is best to ensure that GC activity does not take too long to complete.
cpuUtil	Indicates the average percentage of CPU utilized by the garbage collection operations of this type.	Percent	A high value for this measure indicates that the load on the target server is high and there are less CPU resources available for the functioning of the server.
objMemFreed	Indicates the amount of memory released by the objects per garbage collection operation of this type.	Collections/min	A high value is indicative of frequent garbage collections. This could be owing to rapid and significant heap growth on the node. Frequent garbage collections on a node may degrade its performance. To avoid this, you may want to consider resizing the heap on that node.
objMem	Indicates the rate at which garbage collection operations of this type occurred.	MB/collection
classMemFreed	Indicates the amount of memory released by the loaded classes per garbage collection operation of this type.	MB/collection
classMem	Indicates the amount of memory that is currently occupied by the loaded classes per garbage collection of this type.	MB/collection
heapSize	Indicates the amount of Java heap memory allocated to the objects per garbage collection operation of this type.	MB/collection
classUnload	Indicates the number of classes currently unloaded per garbage collection operation of this type.	Classes/collection