When does the Netprobe connect to the JMX enabled Java application

It connects on the plugin's first sample and reuses the connection for succeeding samples.

It connects on the plugin's first sample. Once the connection is established, the Netprobe reuses the connection for succeeding samples.

For example:

The effect of this is that the Netprobe will create only 2 connections:

The Netprobe will also keep the connection open. Sampler 01 and Sampler 02 will share 1 connection to Java app A.