JProfiler Get rid of your performance problems and memory leaks! Modern Garbage Collection Tuning Java Performance Training Courses COURSES AVAILABLE NOW. We can provide training courses to handle all your Java performance needs Java Performance Tuning, 2nd ed The classic and most comprehensive book on tuning Java Java Performance Tuning Newsletter Your source of Java performance news. Subscribe now! Enter email: Training online Threading Essentials course JProfiler Get rid of your performance problems and memory leaks!

Back to newsletter 276 contents

The number of JVM configuration options that you can change dynamically has always been very limited. You can see the (fairly short) list with java -XX:+PrintFlagsFinal -version | [grep|findstr] "manageable" (grep on Unix, findstr on Windows).

Part of the reason is that the process data structure of the JVM is dramatically different depending on which GC algorithm is chosen (so it's hugely unlikely that the choice of GC algorithm will ever be dynamically alterable). Part of the reason is that it's much much easier programmatically to check a value at (lazy) initialization and assume that value is never subsequently changed asynchronously. If you have to assume a value can be changed at any time, you have the full overhead of concurrent programming considerations to work through, something people are very bad at. Immutable values and structures and objects are much more efficient to manage and to reason about. This is especially true for performance.

So we're unlikely to see that list ever grow significantly, even though some JVM options would be very useful to change dynamically. Now on to all the usual newsletter list of links, tips, tools, news and articles, and as usual I've extracted all the tips into this month's tips page

A note from this newsletter's sponsor

News

Java performance tuning related news

• OpenJ9 supports CRIUSupport class for checkpoint and restore (with -XX:+EnableCRIUSupport and criu command)
• List of common performance antipatterns
• Understanding how GC pauses can interact with latency measurements

Tools

Java performance tuning related tools

• Rate-limiting library based on token-bucket algorithm
• Guava rate limiter
• List of basic thread safety techniques (synchronized, Atomic* variables, volatile, immutability)

Articles

• The A-Z guide to Distributed Caching (Haasita Pinnepu/Medium)
• Decoding the secrets of the JVM internals (Lennart ten Wolde/J-Spring)
• A Simple Approach to the Advanced JVM Profiling (Andrei Pangin/IntelliJ IDEA)

Jack Shirazi

Back to newsletter 276 contents