Richard Pajerski Software development and consulting

Entries tagged [j9]

Eclipse J9 is a big deal

by Richard Pajerski

Posted on Friday March 15, 2019 at 11:59PM in Technology

Having developed with Java for a number of years in various environments (Notes/Domino, Tomcat, ActiveMQ,  Android, desktop, etc.), I was initially skeptical when I read this article and watched the video about the recently-improved Eclipse OpenJ9:

Yes, Java has incrementally improved over time but the claims here seemed a bit over the top.  To think I might get both noticeably faster startup *and* up to 50% memory reduction just by switching to J9 seemed to be a bit too optimistic.  But after downloading ( and giving it a spin, I was not disappointed.

Sure enough, out-of-the-box startup time for Netbeans 8.2 on Windows 8.1 increased dramatically against Oracle Java 1.8.0_191 (running quad-core I7 on SSD).  There was no point in taking measurements -- it was up and ready in three seconds!  This didn't seem possible with Netbeans but there it was.  Everything worked the same as before ... only faster.  Then the real shocker: RAM usage went from roughly 650M down to 268!  Huh?  If I can eliminate that much RAM usage for hosted server side deployments, it's going to translate into real cash savings.

On top of the performance upgrade and memory savings, I immediately noticed that Swing is visually better in J9 than OpenJDK [edit: with the HotSpot VM].  In particular, the default font rendering is really nice!  In the past, OpenJDK has generally lagged behind Oracle Java for desktop applications and still does; but to my eyes, J9 is now at visual parity with Oracle (or perhaps better).

I realize that the J9 has been the JVM in Notes/Domino all these years but I've never attempted to benchmark it against other JVMs since IBM never really promoted it as a JDK for Windows.  I'm currently using 9.0.1 FP10 which uses build of J9:


Hopefully, IBM can manage to get the latest J9 into an upcoming fixpack.  I sure have lots of Notes and Domino Java code that could benefit from it.

A big congratulations and thank you to Mark Stoodley and all the other engineers and players behind this release!