I'm trying to run some software that relies on Java. Currently I have:

~ » java --version                                                                                                                                         jpage@LMDP-PJacob
java 9.0.4
Java(TM) SE Runtime Environment (build 9.0.4+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.4+11, mixed mode)

I'm getting a runtime error for the application (Cassandra):

Improperly specified VM option 'ThreadPriorityPolicy=42'

...so figured I may need to upgrade to a newer version of Java. I see there's a Java 13, but I seem to only be able to download the entire JDK from Oracle's download page. Since I do not plan on doing any Java development, I'd rather not clutter up my HD with a bunch of development crap.

Does the world of Java still have the concept of a distinct JRE versus JDK? If so, why can't I find the download for just the JRE? Or am I getting some stuff confused? Java versioning has long been confusing to me.


This is a known problem with Cassandra. To solve it, you would actually have to downgrade to Java 8.

If you don't want to downgrade, just go to config/jvm.options in your Cassandra directory.

Open the file in a text editor and remove the line -XX:ThreadPriorityPolicy=42.

| improve this answer | |
  • I did comment out that line, but got hit with even more unsupported flags. I'm thinking there's no good way to get it working with newer Javas, so I did end up running it with Java 8. I'm still curious about my main question on how it's possible to just install the JRE for later Javas; is that even supported now, or do you always have to install JDKs now? – Jacob Nov 22 '19 at 18:21
  • 1
    @Jacob, take a look at this article: dzone.com/articles/no-more-jre-packaging-no-big-deal-1 Fortunately, the AdoptOpenJDK team does a great job and provide JRE-only binaries: adoptopenjdk.net – cesarse Jan 20 at 13:16

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