|
|
|
|
Back to newsletter 197 contents
Half a year ago I listed and explained almost all the changes in Java 9 that have a performance impact. This month, courtesy of Tony Printezis (who I'll come back to later), there's a few more of those Java 9 performance related changes for me to list.
Firstly, JEP 295 gives us an ahead-of-time Java compiler. Yes, in Java 9, you can actually create a compiled object library from Java code that will be loaded into the JVM! This is targeted at applications and utilities that need quick startup time, I suspect if instead you need optimal speed after warmup, you are better off sticking to the traditional startup of loading .class/.jar and equivalent types of files. And, at least in this first release, it has too many limitations to be useful for most applications.
Next, and I've already mentioned this several times, not least in my complete list of Garbage Collector combinations, we're losing several combinations of garbage collectors in Java 9, as covered in JEP 214. The only one of these that was particularly useful was "ParNew + SerialOld : -XX:+UseParNewGC", which was the optimal garbage collector combination if you were targeting footprint size in bi-stable heaps (heaps where Xms and Xmx are set to different values and under normal operation the heap stabilizes at one lower value, but where occasionally operational flow changes to require a different higher stable heap size). Bi-stable heaps are the norm when you have an in-memory queue that is used for smoothing occasional spikes. If you need to tune the footprint of a bi-stable heap in Java 9, the only option becomes the serial collector which sadly has really bad young generation pause times.
Finally there's JEP 271 and JEP 158 - unified logging. And for more on these, you want to head down to the articles listed in this newsletter and click on Tony Printezis' talk - generally, if Tony is giving a garbage collection talk you should make the time to see it, they are always top quality, extremely useful, and imho essential viewing for the performance community.
Now on to those links to articles, tools, news, talks, blogs. And if you need the tips from this month's articles and talks, as ever they are extracted into this month's tips page.
Java performance tuning related news.
Java performance tuning related tools.
Back to newsletter 197 contents
