Monitor Garbage Collection
The Java Agent reports certain Garbage Collection metrics at one-minute intervals. You can view these metrics on the Heap & Garbage Collection sub-tab of the Memory tab on the Node dashboard:
- Heap utilization
- Free, used, committed, and available.This is the most coarse-grained view of memory use.
- Garbage Collection
- Minor, major, and total on one timeline.This should give you some notion of the ratio of minor to major collections.
- Minor Garbage Collection
- On a timeline.
- Major Garbage Collection
- On a timeline.
- Memory pool use
- Including the use of all memory spaces: Young Generation, Old Generation, and PermGen.
For a finer-grained view of the impact of Garbage Collection on application performance, you can view Garbage Collection metrics in the Metric Browser. Navigate to .
In addition to the periodically-collected metrics, the Metric Browser shows the following metrics triggered by minor or major Garbage Collection events:
| Metric | Triggering Event | Description |
|---|---|---|
|
Allocated-Objects |
Minor collection |
The amount of memory allocated to the Young Generation. A high growth rate might indicate memory thrash. The allocation rate affects the frequency of minor collection events, which can impact application performance over time. The value for Count indicates how many collections were made. |
| Promoted-Objects | Major collection |
The amount of memory in use for objects promoted from Young Gen space to Old Gen space. A high promotion rate is related to major collection events, which can have a significant impact on application performance due to the duration of a full major collection cycle. If the promotion rate is close to the allocation rate, this might indicate premature promotion. In this case, you might want to allocate more memory to Young Gen space. The value for Count indicates how many collections were made. |
| Freed Objects |
Minor or Major collection |
The amount of memory in use for objects being reclaimed in Young and Old space. In a normal system, the number of objects allocated and the free rate metrics should be roughly equal. The value for Count indicates how many collections were made. |
| LiveData | Major collection |
The amount of memory in use that persists after major Garbage Collections. An upward slope in the size of live data indicates a possible memory leak. |