Re: Running tests in parallel?

Dear All.

On Mon, 2021-11-01 at 14:36 +0700, Andreas Reichel wrote:
> Am I right that most of the Use Cases tests are executed serially
> (only)?

Looks like I was semi-right:
// set heap size for the test JVM(s)
minHeapSize = "128m"
maxHeapSize = "1512m"

// Specifying the local via system properties did not work, so we set them this way
jvmArgs << [
    '-Djava.io.tmpdir=build',
    '-DPOI.testdata.path=../test-data',
    '-Djava.awt.headless=true',
    '-Djava.locale.providers=JRE,CLDR',
    '-Duser.language=en',
    '-Duser.country=US',
    '-Djavax.xml.stream.XMLInputFactory=com.sun.xml.internal.stream.XMLInputFactoryImpl',
    "-Dversion.id=${project.version}",
    '-ea',
    '-Djunit.jupiter.execution.parallel.config.strategy=fixed',
    '-Djunit.jupiter.execution.parallel.config.fixed.parallelism=2'
    // -Xjit:verbose={compileStart|compileEnd},vlog=build/jit.log${no.jit.sherlock}   ... if ${isIBMVM}
]


Questions please:

1) why do we not allocate maxHeapSize dynamically based on the (Free)
Memory of the OS, e.g. use 50% of that memory?
2) why do we not allocate all Cpu Cores, but just 2? What advantage do
the following lines have:
'-Djunit.jupiter.execution.parallel.config.strategy=fixed',
'-Djunit.jupiter.execution.parallel.config.fixed.parallelism=2'

Best regards
Andreas