During a load test, run a single user for 1 iteration on the localhost LG (aka the Controller), this user can run a userpath containing some javascript that gets the hostname and stores it on a shared queue or in a constant variable (see context.CurrentLG.name). One thing to note, the "context.CurrentLG.name" method will return the name or IP that was used when you discovered your load generator. So if you would like to get the hostname make sure to discover your load generators using their hostnames. That includes the local load generator. That said, as you are running the test, you could pass in the hostname as a parameter on the command line using the variables switch