-Xss jvm opt for bloop seems to not work

[hilaolu]

Hi, I am using vscode+metal and I am trying to migrate a Chisel project from sbt to mill. I got a java stack overflow error during unit test. I have confirmed this is cause by insufficient stack space. The -Xss arg of original sbt project is 32m while the default of bloop is 4m. I have search issues of metal project for how to modify jvm opt. I tried

• $PROJECT_FOLDER/.bloop/bloop.json
• $PROJECT_FOLDER/.bloop/.jvmopts
• $PROJECT_FOLDER/.jvmopts
• $PROJECT_FOLDER/.mill-jvm-opts
• ~/.bloop/bloop.json
• ~/.bloop/.jvmopts
• Adding -Xss in vscode plugin settings.

And I saw -Xss32m really appeared on java args, with -Xss4m. But the stack overflow problem is still. How can I determind whether the -Xss opt really takes effect?
Thanks

[dos65]

@hilaolu setting it in ~./bloop/.jvmopts should work.
Could you ensure that after applying modification in this file you restarted the bloop process?

[hilaolu]

Restarted many times!

[kpodsiad]

EDIT: Answer to the question is at the end of this thread.

The easiest way to achieve your goal is:

• add -Xss to the ~/.bloop/bloop.json

{
  "javaOptions": ["-Xss32m"]
}

or ~/.bloop/.jvmopts

-Xss32m

• restart bloop either via metals restart build server OR command line (if you installed bloop by yourself) bloop ng-stop and then run connect to the build server in metals

Then you can search for Bloop process via ps or htop and see its arguments.

[kpodsiad]

Do you run those unit tests via code lenses?

[hilaolu]

No idea about code lense ( I am new to vscode).
I just click the test on class in vscode editor

[dos65]

@hilaolu As an option you can try to use mill-bsp server
I don't know if it will work but there is a chance that it runs tests with correct jvm options specified in build.

[kpodsiad]

Yeah, so these things are called code lenses

Currently, as I wrote earlier, there it's not possible to add JVM option to test runned via code lenses if you're using Bloop as build server. However, you could use bloop CLI to run your tests and add JVM options to test run. But keep in mind that you have to have Bloop installed (how to install bloop).

[hilaolu]

Thank you all!

[kpodsiad]

@hilaolu It should be possible to define java options in mill like it was done in sbt. Could you try override def forkArgs = Seq("-Xss32m")? I checked it myself and it seems to work.

[hilaolu]

Hi, @kpodsiad. I didn't modify anything and it works. It seems that .mill-jvm-opt or .jvmopts works. Thank you and I really enjoy working with metals.