State which Java versions are supported

[chrisbroome]

Issue

There needs to be some documentation on which Java versions are supported.

Background

I just tried running the tour, but I'm getting an exception. I suspect the problem is that I'm using Java >= 9, (in my case, Java 11), and there were changes to the way class loaders worked?

I also tried updating the accumulo.version to 1.9.2 in the pom.xml but that had no effect.

Here's the last few lines of my output (no quiet mode):

Command

$ mvn clean compile exec:java

Output

[INFO] --- exec-maven-plugin:1.5.0:java (default-cli) @ accumulo-tour ---
Running the Accumulo tour. Having fun yet?
[WARNING]
java.lang.reflect.InvocationTargetException
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:294)
    at java.lang.Thread.run (Thread.java:834)
Caused by: java.lang.IllegalArgumentException: Unknown classloader type : jdk.internal.loader.ClassLoaders$AppClassLoader
    at org.apache.accumulo.minicluster.impl.MiniAccumuloClusterImpl.getClasspath (MiniAccumuloClusterImpl.java:270)
    at org.apache.accumulo.minicluster.impl.MiniAccumuloClusterImpl._exec (MiniAccumuloClusterImpl.java:288)
    at org.apache.accumulo.minicluster.impl.MiniAccumuloClusterImpl._exec (MiniAccumuloClusterImpl.java:364)
    at org.apache.accumulo.minicluster.impl.MiniAccumuloClusterControl.start (MiniAccumuloClusterControl.java:161)
    at org.apache.accumulo.minicluster.impl.MiniAccumuloClusterControl.start (MiniAccumuloClusterControl.java:137)
    at org.apache.accumulo.minicluster.impl.MiniAccumuloClusterControl.start (MiniAccumuloClusterControl.java:69)
    at org.apache.accumulo.minicluster.impl.MiniAccumuloClusterImpl.start (MiniAccumuloClusterImpl.java:571)
    at org.apache.accumulo.minicluster.MiniAccumuloCluster.start (MiniAccumuloCluster.java:70)
    at tour.Main.main (Main.java:29)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:294)
    at java.lang.Thread.run (Thread.java:834)
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.726 s
[INFO] Finished at: 2019-01-25T16:09:43-05:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.5.0:java (default-cli) on project accumulo-tour: An exception occured while executing the Java class. null: InvocationTargetException: Unknown classloader type : jdk.internal.loader.ClassLoaders$AppClassLoader -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

Java version:

$ java -version
java version "11.0.1" 2018-10-16 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.1+13-LTS)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.1+13-LTS, mixed mode)

Maven version:

$ mvn -v
Apache Maven 3.6.0 (97c98ec64a1fdfee7767ce5ffb20918da4f719f3; 2018-10-24T14:41:47-04:00)
Maven home: /usr/local/Cellar/maven/3.6.0/libexec
Java version: 11.0.1, vendor: Oracle Corporation, runtime: /Library/Java/JavaVirtualMachines/jdk-11.0.1.jdk/Contents/Home
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.14.2", arch: "x86_64", family: "mac"

[keith-turner]

It does seem like it is an issue with Java 11 and mini Accumulo. In the short term, I think adding info about supported java versions to the tour makes sense for now. We need to open an accumulo issue and look into getting mini working with Java 11. Hopefully there is something that can be done so that mini works with Java 8 and Java 11.

[keith-turner]

@chrisbroome thanks for letting us know about the problem. I added a disclaimer about Java 11 to the first page of the tour.