Support for Java

The support matrix for the Java versions for compiling and running Apache Cassandra is detailed in Table 1. The build version is along the vertical axis and the run version is along the horizontal axis.

Support Matrix for Java

Java 11 (Run)

Java 17 (Run)

Java 11 (Build)

Supported

Supported

Java 17(Build)

Not Supported

Experimental

Apache 4.0 source code built with Java 17 cannot be run with Java 11. All binary releases are built with Java 11.

Using Java 17 to Build

To start with, install Java 17. As an example, for installing Java 17 on RedHat Linux the command is as follows:

  1. $ sudo yum install java-17-openjdk

Set the environment variables JAVA_HOME and PATH.

  1. $ export JAVA_HOME=/usr/lib/jvm/java-17-openjdk
  2. $ export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin

Download and install Apache Cassandra 5.0 source code from the Git along with the dependencies.

  1. $ git clone https://github.com/apache/cassandra.git

If Cassandra is already running stop Cassandra with the following command.

  1. $ ./nodetool stopdaemon

Build the source code from the cassandra directory, which has the build.xml build script. The Apache Ant uses the Java version set in the JAVA_HOME environment variable.

  1. $ cd ~/cassandra
  2. $ ant

Apache Cassandra 5.0 gets built with Java 11. Set the environment variable for CASSANDRA_HOME in the bash script. Also add the CASSANDRA_HOME/bin to the PATH variable.

  1. $ export CASSANDRA_HOME=~/cassandra
  2. $ export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin:$CASSANDRA_HOME/bin

To run Apache Cassandra 5.0 with either of Java 11 or Java 17 run the Cassandra application in the CASSANDRA_HOME/bin directory, which is in the PATH env variable.

  1. $ cassandra

The Java version used to run Cassandra gets output as Cassandra is getting started. As an example if Java 11 is used, the run output should include similar to the following output snippet:

  1. INFO  [main] 2019-07-31 21:18:16,862 CassandraDaemon.java:480 - Hostname: ip-172-30-3-
  2. 146.ec2.internal:7000:7001
  3. INFO  [main] 2019-07-31 21:18:16,862 CassandraDaemon.java:487 - JVM vendor/version: OpenJDK
  4. 64-Bit Server VM/11.0.3
  5. INFO  [main] 2019-07-31 21:18:16,863 CassandraDaemon.java:488 - Heap size:
  6. 1004.000MiB/1004.000MiB

The following output indicates a single node Cassandra 5.0 cluster has started.

  1. INFO  [main] 2019-07-31 21:18:19,687 InboundConnectionInitiator.java:130 - Listening on
  2. address: (127.0.0.1:7000), nic: lo, encryption: enabled (openssl)
  3. ...
  4. ...
  5. INFO  [main] 2019-07-31 21:18:19,850 StorageService.java:512 - Unable to gossip with any
  6. peers but continuing anyway since node is in its own seed list
  7. INFO  [main] 2019-07-31 21:18:19,864 StorageService.java:695 - Loading persisted ring state
  8. INFO  [main] 2019-07-31 21:18:19,865 StorageService.java:814 - Starting up server gossip
  9. INFO  [main] 2019-07-31 21:18:20,088 BufferPool.java:216 - Global buffer pool is enabled,
  10. when pool is exhausted (max is 251.000MiB) it will allocate on heap
  11. INFO  [main] 2019-07-31 21:18:20,110 StorageService.java:875 - This node will not auto
  12. bootstrap because it is configured to be a seed node.
  13. ...
  14. ...
  15. INFO  [main] 2019-07-31 21:18:20,809 StorageService.java:1507 - JOINING: Finish joining ring
  16. INFO  [main] 2019-07-31 21:18:20,921 StorageService.java:2508 - Node 127.0.0.1:7000 state
  17. jump to NORMAL

Using Java 11 to Build

If Java 17 is used to build Apache Cassandra 5.0, first Java 11 must be installed and the environment variables set. As an example, to download and install Java 11 on RedHat Linux run the following command.

  1. $ yum install java-11-openjdk

Set the environment variables JAVA_HOME and PATH.

  1. $ export JAVA_HOME=/usr/lib/jvm/java-11-openjdk
  2. $ export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin

The build output should now include the following.

  1. [echo] Non default JDK version used: 11
  2. ...
  3. ...
  4. _build_java:
  5.     [echo] Compiling for Java 11
  6. ...
  7. ...
  8. build:
  10. _main-jar:
  11.          [copy] Copying 1 file to /home/ec2-user/cassandra/build/classes/main/META-INF
  12.      [jar] Building jar: /home/ec2-user/cassandra/build/apache-cassandra-4.0-SNAPSHOT.jar
  13. ...
  14. ...
  15. _build-test:
  16.    [javac] Compiling 739 source files to /home/ec2-user/cassandra/build/test/classes
  17.     [copy] Copying 25 files to /home/ec2-user/cassandra/build/test/classes
  18. ...
  19. ...
  20. jar:
  21.    [mkdir] Created dir: /home/ec2-user/cassandra/build/classes/stress/META-INF
  22.    [mkdir] Created dir: /home/ec2-user/cassandra/build/tools/lib
  23.      [jar] Building jar: /home/ec2-user/cassandra/build/tools/lib/stress.jar
  24.    [mkdir] Created dir: /home/ec2-user/cassandra/build/classes/fqltool/META-INF
  25.      [jar] Building jar: /home/ec2-user/cassandra/build/tools/lib/fqltool.jar
  27. BUILD SUCCESSFUL
  28. Total time: 1 minute 3 seconds

Common Issues

The Java 17 built Apache Cassandra 5.0 source code may be run with Java 17 only. If a Java 17 built code is run with Java 11 the following error message gets output.

  1. # ssh -i cassandra.pem ec2-user@ec2-3-85-85-75.compute-1.amazonaws.com
  2. Last login: Wed Jul 31 20:47:26 2019 from 75.155.255.51
  3. $ echo $JAVA_HOME
  4. /usr/lib/jvm/java-11-openjdk
  5. $ cassandra
  6. ...
  7. ...
  8. Error: A JNI error has occurred, please check your installation and try again
  9. Exception in thread "main" java.lang.UnsupportedClassVersionError:
  10. org/apache/cassandra/service/CassandraDaemon has been compiled by a more recent version of
  11. the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes
  12. class file versions up to 52.0
  13.   at java.lang.ClassLoader.defineClass1(Native Method)
  14.   at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
  15.   at ...
  16. ...