> Is the configured amount of tasks for reuse a suggestion or will it actually > use it? For example, if I’ve configured it to use a JVM for 4 tasks, will a > TaskTracker that has 8 tasks to process use 2 JVMs? Or does it decide if it > actually wants to reuse one up to the maximum configured number?
It will launch mapred.tasktracker.map.tasks.maximum + mapred.tasktracker.reduce.tasks.maximum JVMs. If a job has more than that many tasks for that task tracker, it will then reuse those. > Will a TaskTracker use the same JVM for tasks from different jobs? Related > to this, will a TaskTracker idle a JVM until it has enough tasks to fit the > maximum JVM reuse variable? It will not reuse JVMs across jobs. When the job finishes, all task JVMs will be shutdown. -Joey -- Joseph Echeverria Cloudera, Inc. 443.305.9434
