What is a container in YARN?

Question

What is a container in YARN? Is it same as the child JVM in which the tasks on the nodemanager run or is it different?

Answer 1

Word 'Container' is used in YARN in two contexts,

Container: Signifies an allocated resources to an ApplicationMaster. ResourceManager is responsible for issuing resource/container to an ApplicationMaster. Check Container API.

Launching a Container: Based on allocated resources (containers) ApplicationMaster request NodeManager to start Containers, resulting in executing task on a node. Check ContainerManager API.