Mr N

I haven't done any groovy for a while and when I ran my groovy command I got this:

$ groovy
Error occurred during initialization of VM
java.lang.Error: Could not create SecurityManager
    at java.lang.System.initPhase3(java.base@11.0.2/System.java:2057)
Caused by: java.lang.ClassNotFoundException: allow
    at jdk.internal.loader.BuiltinClassLoader.loadClass(java.base@11.0.2/BuiltinClassLoader.java:583)
    at jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(java.base@11.0.2/ClassLoaders.java:178)
    at java.lang.ClassLoader.loadClass(java.base@11.0.2/ClassLoader.java:521)
    at java.lang.Class.forName0(java.base@11.0.2/Native Method)
    at java.lang.Class.forName(java.base@11.0.2/Class.java:398)
    at java.lang.System.initPhase3(java.base@11.0.2/System.java:2042)

I reinstalled groovy with brew reinstall groovy but it didn't make any difference. After a bit of Googling I found a solution.

1. Locate you groovy executable. Mine is in /usr/local/bin/groovy
2. Load it into you favourite editor and modify the security manager name from java.security.manager to java.security.SecurityManager, as follows:

JAVA_HOME="${JAVA_HOME:-/usr/local/opt/openjdk/libexec/openjdk.jdk/Contents/Home}" JAVA_OPTS="$JAVA_OPTS -Djava.security.manager=allow" exec "/usr/local/Cellar/groovy/4.0.1_1/libexec    /bin/groovy"  "$@"

to

JAVA_HOME="${JAVA_HOME:-/usr/local/opt/openjdk/libexec/openjdk.jdk/Contents/Home}" JAVA_OPTS="$JAVA_OPTS -Djava.security.SecurityManager=allow" exec "/usr/local/Cellar/groovy/4.0.1_1/libexec    /bin/groovy"  "$@"

That's it! Do you same for the other groovy supporting programs like: groovyConsole, groovyConsole_completion, groovy_completion, groovyc, groovyc_completion, groovydoc, groovydoc_completion, groovysh, groovysh_completion, also located in /usr/local/bin.

When trying to workout why a maven build is failing, I used these options to switch on JMX support inside Maven. Once Maven was running I connected jconsole to read the stats.

Log lines have their thread name:

MAVEN_OPTS=" -Dorg.slf4j.simpleLogger.showThreadName=true"

Port to listen on:

MAVEN_OPTS+=" -Dcom.sun.management.jmxremote.port=9010"

Allow remote connections:

MAVEN_OPTS+=" -Dcom.sun.management.jmxremote.local.only=false"

Switch off authentication:

MAVEN_OPTS+=" -Dcom.sun.management.jmxremote.authenticate=false"

Make sure app binds to the external interface:

MAVEN_OPTS+=" -Djava.rmi.server.hostname=vmware"

Make sure no security stuff gets in the way:

MAVEN_OPTS+=" -Djava.security.policy=all.policy"

Switch off SSL, so there is no complaining about certificates:

MAVEN_OPTS+=" -Dcom.sun.management.jmxremote.ssl=false"

Here are a few Maven things I want to remember:

This is a great one. The colouring of the circle bands, tricks your eyes into thinking that the circle starts at different places.

I had a look for the original source but it's copied across Twitter and Redit. Couldn't find anything else.

All the balls are the same colour!

Credit: Derren Brown linked to Daniell Owengrub's blog which linked to SyFy which linked to David Novick (creator of image)