Hi guys, patch http://gerrit.ovirt.org/#/c/36739/ just landed in master branch. It adds two new Makefile variables: # Maven JVM options. BUILD_JAVA_OPTS_MAVEN # GWT compiler & DevMode JVM options. BUILD_JAVA_OPTS_GWT Use BUILD_JAVA_OPTS_MAVEN to specify JVM arguments for main "mvn" command. Default value is "-XX:MaxPermSize=512M" which should be OK for most cases. Use BUILD_JAVA_OPTS_GWT to specify JVM arguments for GWT compiler & DevMode. Default value is "" which translates into following fallback value: # gwt.jvmArgs fallback in frontend/webadmin/modules/pom.xml -Xms1024M -Xmx8192M -XX:PermSize=512M -XX:MaxPermSize=1024M Custom BUILD_JAVA_OPTS_GWT (non-empty string) value will be translated into -Dgwt.jvmArgs="..." when invoking main "mvn" command. TL;DR Engine build should work without any JVM argument tuning as before. If you're running into "java.lang.OutOfMemoryError" during the build, we suggest to limit max. simultaneous GWT permutation worker threads to 1 and tune GWT compiler JVM arguments according to your system: $ export BUILD_JAVA_OPTS_MAVEN="-XX:MaxPermSize=512M -Dgwt.compiler.localWorkers=1" $ export BUILD_JAVA_OPTS_GWT="-Xms1024M -Xmx4096M -XX:MaxPermSize=1024M" Regards, Vojtech