Setting Baseline to monitor performance

I'm not really sure what you're asking here.

I should clarify, however, what these baseline values mean. They are, in general, cumulative/aggregate statistics since the baseline for the statistic in question was last reset. Unless you take explicitly action to do such a reset, this means the statistics apply to the entire life of the server process in question, i.e. the start of the server (or monitoring MBean in question) serves as a default baseline.

As far as resetting a baseline, I should clarify a bit there as well. This simply means taking a snapshot of various statistics (including the current time) at the current point in time -- and using those in the computation of future baseline statistics. Thus resetting a baseline means that baseline statistics will reflect the time period from the time of reset to the current time -- rather than from system startup to the current point in time.

As far as how you actually reset a baseline, the corresponding JMX MBeans which collect the statistics in question expose an operation to reset a baseline. You can invoke this on an individual MBean via the jconsole or VisualVM UI.

If you want to invoke this operation on numerous MBeans in very quick succession and/or apply this to all servers in the cluster, then you'll need to write a short bit of code to do this (using the MethodServerMProxy MBean for cluster-multicast as needed). This code can be written in Java -- or in 10.0 and higher you can install and use your favorite javax.script (the Java 6+ Scripting API) compatible scripting language. A JavaScript engine is built into Java 6 and higher. In any case, however, the API calls are much the same.