[FIXED] How can I decrease the memory heap for my scala project using Sbt?

Issue

I am building a javafx project with scala and I have noticed that the memory usage is over 170mb and a blank javafx project is about 90mb. I saw the JavaFX eats my memory? page and it says that most of the memory in the heap is not being used an explains a way to shrink the heap by using this flag: --XX:+UseG1GC. I tried this in sbt by using: javacOptions += "--XX:+UseG1GC" In Sbt but the memory usage stayed the same. Can anybody help me shrink this heap?

Solution

If you use SBT native packager in you project, in addition to JVM_OPTS and .jvmopts you may add flags (or some other custom commands) to a generated execution script. That's how we do it in our project:

    project.in(file("example")).settings(
      batScriptExtraDefines ++= Seq( //Windows bat/cmd
        """set _JAVA_OPTS=!_JAVA_OPTS! -Djdk.tls.ephemeralDHKeySize=2048""",
        """set _JAVA_OPTS=!_JAVA_OPTS! -Djdk.tls.rejectClientInitiatedRenegotiation=true"""
      ),

      bashScriptExtraDefines ++= Seq( //Unix shell
        """addJava "-Djdk.tls.ephemeralDHKeySize=2048"""",
        """addJava "-Djdk.tls.rejectClientInitiatedRenegotiation=true"""",
        """umask 077"""
      )
    )

Answered By - den_po