Fix/actually limit memory for client (#5026)

Properly implements fix done in
#4163

Also adds JVisualVM support for native mill image.

Tested manually by launching both the JVM and native versions and
looking at the memory usage during compilation via JVisualVM

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Li Haoyi <[email protected]>

Author: 3 people

dist/package.mill

@@ -82,6 +82,11 @@ object `package` extends MillJavaModule with DistModule {
 
   def localBinName = "mill-assembly.jar"
 
+  private def millClientJvmArgs = Seq(
+    // Avoid reserving a lot of memory for the client, as the client only forward information
+    "-Xmx128m"
+  )
+
   def launcher = Task {
     val isWin = scala.util.Properties.isWin
     val outputPath = Task.dest / (if (isWin) "run.bat" else "run")
@@ -102,9 +107,7 @@ object `package` extends MillJavaModule with DistModule {
       .mkString("\r\n")
 
     os.write(vmOptionsFile, millOptionsContent)
-    val jvmArgs = otherArgs ++ List(
-      // Avoid reserving a lot of memory for the client, as the client only forward information
-      "-Xmx32m",
+    val jvmArgs = otherArgs ++ millClientJvmArgs ++ List(
       s"-DMILL_OPTIONS_PATH=$vmOptionsFile"
     )
     val classpath = runClasspath().map(_.path.toString)
@@ -129,7 +132,7 @@ object `package` extends MillJavaModule with DistModule {
     mill.scalalib.Assembly.Rule.ExcludePattern("mill/local-test-overrides/.*")
   )
 
-  def forkArgs = Seq(
+  def forkArgs = millClientJvmArgs ++ Seq(
     // Workaround for Zinc/JNA bug
     // https://github.com/sbt/sbt/blame/6718803ee6023ab041b045a6988fafcfae9d15b5/main/src/main/scala/sbt/Main.scala#L130
     "-Djna.nosys=true"
@@ -278,7 +281,14 @@ object `package` extends MillJavaModule with DistModule {
       PathRef(executable)
     }
 
-    def nativeImageOptions = Seq("--no-fallback", "--enable-url-protocols=https", "-Os")
+    def nativeImageOptions = Seq(
+      "--no-fallback",
+      "--enable-url-protocols=https",
+      "-Os"
+      // Enable JVisualVM support
+      // https://www.graalvm.org/latest/tools/visualvm/#using-visualvm-with-graalvm-native-executables
+      // "--enable-monitoring=jvmstat,heapdump"
+    )
 
     def jvmWorker = ModuleRef(JvmWorkerGraalvm)