Bytecode version is controlled by javac "-target" option for Java, and by scalac "-target:" for Scala JDK can cross-compile between known versions.
Spark uses 1.8 as source and target by default controlled by the Maven property java.version <https://github.com/apache/spark/blob/00d7094dc3024ae594605b311dcc55e95d277d5f/pom.xml#L109>. But it's also hard-coded with -target:jvm-1.8 <https://github.com/apache/spark/blob/00d7094dc3024ae594605b311dcc55e95d277d5f/pom.xml#L2891> for Scala. Higher JDK versions can run lower version bytecode. if you want to try 11, replace occurences -target:jvm-1.8 by --target:jvm-${java.version} in pom.xml you should be able to produce 11 bytecode by adding -Djava.version=11 to your Maven build command. ./build/mvn -Djava.version=11 ... However, I did not try beyond a quick compile on core and cannot say anything about fallout implications at run time. On Mon, Jul 18, 2022 at 3:49 PM Szymon Kuryło <szymonkur...@gmail.com> wrote: > Ok, so I used a docker image `adoptopenjdk/openjdk11:latest` as a builder, > and still got version 52 classes. > > pon., 18 lip 2022 o 09:51 Stephen Coy <s...@infomedia.com.au> napisał(a): > >> Hi Sergey, >> >> I’m willing to be corrected, but I think the use of a JAVA_HOME >> environment variable was something that was started by and continues to be >> perpetuated by Apache Tomcat. >> >> … or maybe Apache Ant, but modern versions of Ant do not need it either. >> >> It is not needed for modern releases of Apache Maven. >> >> Cheers, >> >> Steve C >> >> On 18 Jul 2022, at 4:12 pm, Sergey B. <sergey.bushma...@gmail.com> wrote: >> >> Hi Steve, >> >> Can you shed some light why do they need $JAVA_HOME at all if >> everything is already in place? >> >> Regards, >> - Sergey >> >> On Mon, Jul 18, 2022 at 4:31 AM Stephen Coy < >> s...@infomedia.com.au.invalid> wrote: >> >>> Hi Szymon, >>> >>> There seems to be a common misconception that setting JAVA_HOME will set >>> the version of Java that is used. >>> >>> This is not true, because in most environments you need to have a PATH >>> environment variable set up that points at the version of Java that you >>> want to use. >>> >>> You can set JAVA_HOME to anything at all and `java -version` will always >>> return the same result. >>> >>> The way that you configure PATH varies from OS to OS: >>> >>> >>> - MacOS use `/usr/libexec/java_home -v11` >>> - On linux use `sudo alternatives --config java` >>> - On Windows I have no idea >>> >>> >>> When you do this the `mvn` command will compute the value of JAVA_HOME >>> for its own use; there is no need to explicitly set it yourself (unless >>> other Java applications that you use insist u[on it). >>> >>> >>> Cheers, >>> >>> Steve C >>> >>> On 16 Jul 2022, at 7:24 am, Szymon Kuryło <szymonkur...@gmail.com> >>> wrote: >>> >>> Hello, >>> >>> I'm trying to build a Java 11 Spark distro using the >>> dev/make-distribution.sh script. >>> I have set JAVA_HOME to point to JDK11 location, I've also set the >>> java.version property in pom.xml to 11, effectively also setting >>> `maven.compile.source` and `maven.compile.target`. >>> When inspecting classes from the `dist` directory with `javap -v`, I >>> find that the class major version is 52, which is specific to JDK8. Am >>> I missing something? Is there a reliable way to set the JDK used in the >>> build process? >>> >>> Thanks, >>> Szymon K. >>> >>> >>> This email contains confidential information of and is the copyright of >>> Infomedia. It must not be forwarded, amended or disclosed without consent >>> of the sender. If you received this message by mistake, please advise the >>> sender and delete all copies. Security of transmission on the internet >>> cannot be guaranteed, could be infected, intercepted, or corrupted and you >>> should ensure you have suitable antivirus protection in place. By sending >>> us your or any third party personal details, you consent to (or confirm you >>> have obtained consent from such third parties) to Infomedia’s privacy >>> policy. http://www.infomedia.com.au/privacy-policy/ >>> >> >>
