Thursday Aug 27, 2015

Just-in-Time Compilation with JITWatch

Want to optimize the performance of your code? Ben Evans and Chris Newland wrap up their three-part series about using JITWatch to understand the just-in-time (JIT) compilation techniques used by the dynamic compiler in Oracle’s Java HotSpot VM. JITWatch is a free, open source tool developed by Newland that analyzes the complex compilation log file output generated by Java HotSpot VM. Among other things, it can help you visualize and understand the optimization decisions made by Java HotSpot VM.

Part 3 describes how to use JITWatch to see the effects that even small source code changes can have on Java HotSpot VM switches. Learn about Sandbox and VM switches features. Sandbox will let you edit code and then compile, execute, and analyze the Java HotSpot VM JIT logs. The VM switches are used to control JIT compilation.

In the September/October edition of Java Magazine Ben and Chris wrote part 2, which focuses on how to examine JIT logs to see what the JIT compiler is doing (and why). Part 1 provides a primer on JIT compilation.

Sunday Sep 30, 2012

Talking JavaOne with Rock Star Charles Nutter

JavaOne Rock Stars, conceived in 2005, are the top rated speakers from the JavaOne Conference. They are awarded by their peers who through conference surveys recognize them for their outstanding sessions and speaking ability. Over the years many of the world’s leading Java developers have been so recognized.

We spoke with distinguished Rock Star, Charles Nutter.

A JRuby Update from Charles Nutter

Charles Nutter of Red Hat is well known as a lead developer of JRuby, a Ruby implementation of Java that is tightly integrated with Java to allow for the embedding of the interpreter into any Java application with full two-way access between the Java and the Ruby code.

Nutter is giving the following sessions at this year’s JavaOne:

  • CON7257 – “JVM Bytecode for Dummies (and the Rest of Us Too)”
  • CON7284 – “Implementing Ruby: The Long, Hard Road”
  • CON7263 – “JVM JIT for Dummies”
  • BOF6682 – “I’ve Got 99 Languages, but Java Ain’t One”
  • CON6575 – “Polyglot for Dummies” (Both with Thomas Enebo)


I asked Nutter, to give us the latest on JRuby. “JRuby seems to have hit a tipping point this past year,” he explained, “moving from ‘just another Ruby implementation’ to ‘the best Ruby implementation for X,’ where X may be performance, scaling, big data, stability, reliability, security, and a number of other features important for today's applications. We're currently wrapping up JRuby 1.7, which improves support for Ruby 1.9 APIs, solves a number of user issues and concurrency challenges, and utilizes invokedynamic to outperform all other Ruby implementations by a wide margin. JRuby just gets better and better.”

When asked what he thought about the rapid growth of alternative languages for the JVM, he replied, “I'm very intrigued by efforts to bring a high-performance JavaScript runtime to the JVM. There's really no reason the JVM couldn't be the fastest platform for running JavaScript with the right implementation, and I'm excited to see that happen.”

And what is Nutter working on currently? “Aside from JRuby 1.7 wrap-up,” he explained, “I'm helping the Hotspot developers investigate invokedynamic performance issues and test-driving their new invokedynamic code in Java 8. I'm also starting to explore ways to improve the general state of dynamic languages on the JVM using JRuby as a guide, and to help the JVM become a better platform for all kinds of languages.”

Originally published on blogs.oracle.com/javaone.


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