Processing Unit instance failed to instantiate with the following exception: "org.jini.rio.core.JSBInstantiationException: java.lang.IllegalArgumentException: A metric named process_cpu_time-total already exists".
The failure was due to an incomplete shutdown sequence of the instance previously instantiated on the same GSC.
Workaround: restart the GSC or install service pack 12.3.1
1. add custom log formatter, under lib/ext
2. Cause split-brain
3. GSM destroys pu, calling PUServiceBeanImpl.stop(), which logs info message "Stopping..." using the custom log formatter, and contextClassLoader.