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Performance Overview

Application performance can be measured using many different metrics, including startup time, ramp-up time, footprint, and response time, as well as throughput. At Eclipse OpenJ9, we keep a watchful eye on all of these metrics, making sensible tradeoffs and providing tuning options that allow the virtual machine (VM) to be optimized for different workloads.

OpenJDK 8 performance with Eclipse OpenJ9

OpenJDK 8 with OpenJ9 demonstrates significantly better performance than OpenJDK 8 with HotSpot

42% faster startup time

Shared classes and Ahead-of-Time (AOT) technologies typically reduce startup time. By using -Xquickstart mode as well, you can reduce startup time by up to 42%.

66% smaller footprint after startup

OpenJ9 is highly optimized for cloud workloads, where minimizing memory footprint is important. Out of the box, the footprint is 66% smaller than HotSpot.

Faster ramp-up time in the cloud

OpenJ9 reaches peak throughput on a single CPU core in 8.5 minutes compared with 30 minutes for Hotspot. Ideal for short-lived VMs running in the cloud.

63% smaller footprint during load

Memory footprint increases rapidly when load is applied. However, at steady state, OpenJ9 consistently used around 63% less physical memory than HotSpot.

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OpenJDK 11 performance with Eclipse OpenJ9

Testing shows similar results for OpenJDK 11; OpenJ9 outperforms HotSpot on startup, ramp up, and footprint

51% faster startup time

By using shared classes cache and AOT technology, OpenJ9 starts in roughly half the time it takes HotSpot.

50% smaller footprint after startup

After startup, the OpenJ9 footprint is half the size of HotSpot, which makes it ideal for cloud workloads.

Faster ramp-up time in the cloud

OpenJ9 reaches peak throughput much faster than HotSpot making it especially suitable for running short-lived applications.

33% smaller footprint during load

Consistent with the footprint results after startup, the OpenJ9 footprint remains much smaller than HotSpot when load is applied.

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