JMH and JDK 22

[Maurizio Cimadamore]

Hi,
earlier today I ran into an issue when trying to run a JMH benchmark on 
a 3rd party maven project.

It seems like the issue is caused by the change in javac’s default 
annotation processing policy [1].

Here are the steps to reproduce the issue:

  * set JAVA_HOME to point to a recent JDK 22 build
  * generate a JMH sample pom file using the following command (this is
    what is advertised in the JMH github page [2]):

|$ mvn archetype:generate \ -DinteractiveMode=false \ 
-DarchetypeGroupId=org.openjdk.jmh \ 
-DarchetypeArtifactId=jmh-java-benchmark-archetype \ 
-DgroupId=org.sample \ -DartifactId=test \ -Dversion=1.0 |

  * build the project using |mvn clean package|
  * run the benchmark as follows:

|$ $JAVA_HOME/bin/java -jar target/benchmarks.jar MyBenchmark Exception 
in thread "main" java.lang.RuntimeException: ERROR: Unable to find the 
resource: /META-INF/BenchmarkList at 
org.openjdk.jmh.runner.AbstractResourceReader.getReaders(AbstractResourceReader.java:98) 
at org.openjdk.jmh.runner.BenchmarkList.find(BenchmarkList.java:124) at 
org.openjdk.jmh.runner.Runner.internalRun(Runner.java:252) at 
org.openjdk.jmh.runner.Runner.run(Runner.java:208) at 
org.openjdk.jmh.Main.main(Main.java:71) |

As you can see, there is a problem here, as the META-INF folder does not 
contain the list of benchmarks. This is due to the fact that annotations 
are no longer processed using processors available in the classpath. 
Using JDK 21 to build and run the same pom file works fine.

Adding the following lines to the compiler plugin configuration 
addresses the issue in JDK 22:

|<compilerArgs> <arg>-proc:full</arg> </compilerArgs> |

While this is understandable, I’m afraid that not many users will have 
gotten the memo - I don’t seem to get any notes when building this 
project using JDK 21 (probably the notes are swallowed by maven?). And, 
sadly, the lack of a proper JMH plugin means that all the JMH poms out 
there will need some manual tweaking to keep working in 22.

At the very least, I think that JMH’s maven archetype should be updated 
to include the lines above?

Cheers
Maurizio

[1] - https://github.com/openjdk/jdk/pull/14432
[2] - https://github.com/openjdk/jmh

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