Garbage Collection Tuning in the Java HotSpot Virtual Machine
TS-4887

Users of the Java HotSpot Virtual Machine (HotSpot JVM machine) have several different garbage collectors (GCs) at their disposal, with each GC exhibiting different performance trade-offs. What the GCs have in common, however, is a long list of tuning parameters that enable users to tune many aspects of the GC's behavior. Even though the GCs work quite well out of the box for many applications, sophisticated users with challenging applications need to do some (or a lot of) GC tuning to get the last ounce of performance out of the HotSpot JVM machine.

GC tuning often intimidates users, but there are some easy approaches they can take to make the process more straightforward and effective. This session covers several GC tuning techniques the speakers have developed, based on years of experience with helping their customers, and illustrates their effectiveness with concrete examples.

The presentation covers various GC tuning topics, including

• Tuning advice for the younger generation (space sizing, tenuring threshold tuning, and so on), which is shared among all the GCs in the HotSpot JVM machine
• Specific tuning advice for throughput and low pause, concurrent GCs (tuning GC cycle initiating occupancy, minimizing GC pause times, trade-off between low pause times and high throughput, and so on)
• Miscellaneous topics such as tuning for chip multithreading (CMT) and tuning for multiple JVM machines per system