OpenJ9 class sharing is enabled by default

Class sharing is a feature in Eclipse OpenJ9 that improves your application’s startup performance. It also reduces the memory footprint if the same cache shared across multiple JVMs. Traditionally, this feature is turned on by explicitly specifying option -Xshareclasses in the command line. Default Class Sharing Class data sharing is enabled by default for bootstrap…

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Debugging Java Applications using Watched Fields

Debugging can be quite tedious, complex and cumbersome. Detailed within this blog we will explore how to make Java debugging a bit easier by leveraging the JVM’s embedded debugging tools. Native C/C++ debuggers utilize operating system hooks to debug an application. The Java Virtual Machine (JVM) includes it’s own unique and powerful toolkit for debugging;…

Working With VM Arguments as a Co-op Student

Stereotypically, interns are known to receive the short end of the stick. Whether it’s cleaning up scrappy (and usually unimportant) parts of a project, or doing boring brain-dead tasks that the full-time members are too busy to do, the work that we interns tend to receive is usually viewed as miscellaneous housework. Two weeks into…

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Cgroup Metrics – now available in Javacore

  Eclipse OpenJ9 can now provide Linux cgroup information as part of a Java dump file, commonly known as a javacore. This can be very handy to debug clearly by having the information about the environment in which JVM is running and if JVM is aware of the limits imposed by the environment etc. In…

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New DDR Extensions and ValueTypes

This blog is intended to serve as a technical overview of current Direct Dump Reader (DDR) implementation and an instruction to add new DDR extensions. It is the responsibility of Eclipse OpenJ9 developers to modify DDR whenever there are some changes in J9VM. Additionally, I briefly introduce memory layouts of ValueTypes in J9VM and a…