Understanding YARN and Container Concepts
Apache YARN (Yet Another Resource Negotiator) is the resource management and job scheduling component of the Hadoop ecosystem. It is responsible for managing the computing resources in a Hadoop cluster and scheduling the execution of applications.
YARN Architecture
YARN follows a master-slave architecture, where the master component is the Resource Manager (RM) and the slave components are the Node Managers (NM). The Resource Manager is responsible for managing the cluster's resources, while the Node Managers are responsible for managing the resources on individual nodes.
graph TB
subgraph YARN Architecture
RM[Resource Manager]
NM1[Node Manager 1]
NM2[Node Manager 2]
NM3[Node Manager 3]
RM --> NM1
RM --> NM2
RM --> NM3
end
Container Concept in YARN
In YARN, the basic unit of computation is called a "container". A container represents a collection of physical resources, such as CPU, memory, disk, and network, allocated to a specific application. When an application is submitted to YARN, the Resource Manager allocates the necessary resources and launches the application's tasks as containers on the available Node Managers.
graph TB
subgraph Container Concept
app[Application]
container1[Container 1]
container2[Container 2]
container3[Container 3]
app --> container1
app --> container2
app --> container3
end
Container Lifecycle
The lifecycle of a container in YARN consists of the following stages:
- Requested: The application requests a container from the Resource Manager.
- Allocated: The Resource Manager allocates the requested resources and assigns the container to a Node Manager.
- Launched: The Node Manager launches the container and starts the application's task.
- Running: The application's task is executing within the container.
- Completed: The application's task has finished executing, and the container is released.
By understanding the YARN architecture and the container concept, you can better troubleshoot issues related to container failures in a Hadoop cluster.