Thanks for the answers, they helped me understanding why the thread launches.
I'm using version 4.3 :)
My thoughts were that I call a jbpm api method, and it keeps running on the same thread until it needs further input, or the process ends, but the thread was just confusing me.
I'll take a better look into jobs in the near future, as I'm learning as much as I can about jbpm.
Thanks.