JMeter и OutOfMemory. A research report

This report is dedicated to memory leaks in Apache JMeter tool used for load testing. Sometimes I come across OutOfMemory error during load testing. This error usually spoils load testing metrics and interrupts all testing, and sometimes ruining JMeter load script irrevocably. What I would like to tell about: JMeter memory structure and memory monitoring methods, as well as how to avoid OutOfMemory error and what to do first after it has happened.