[OPENJDK-4106] Enable compact object headers

Signed-off-by: Jonathan Dowland <[email protected]>

Author: jmtd

modules/jvm/artifacts/opt/jboss/container/java/jvm/java-default-options

@@ -81,5 +81,14 @@ error_handling() {
   echo "-XX:+ExitOnOutOfMemoryError"
 }
 
-## Echo options, trimming trailing and multiple spaces
-echo "$(max_memory) $(gc_config) $(diagnostics) $(error_handling)" | awk '$1=$1'
+# OPENJDK-4106
+maybe_compactObjectHeaders() {
+  if [ "$JAVA_COMPACT_OBJECT_HEADERS" != "false" ]; then
+    echo "-XX:+UseCompactObjectHeaders"
+  fi
+}
+
+echo "$(max_memory) $(gc_config) $(diagnostics) $(error_handling)\
+  $(maybe_compactObjectHeaders)
+
+" | awk '$1=$1' # trim leading/trailing spaces and squash multi

modules/jvm/module.yaml

@@ -61,3 +61,6 @@ envs:
 - name:         GC_CONTAINER_OPTIONS
   description:  specify Java GC to use. The value of this variable should contain the necessary JRE command-line options to specify the required GC, which will override the default of `-:+UseParallelGC`.
   example:      -XX:+UseG1GC
+- name:         JAVA_COMPACT_OBJECT_HEADERS
+  description:  Whether to enable compact object headers (JEP519) for JDK24 and newer. Enabled by default.
+  example:      "false"