DecommissioningNodesWatcher (Apache Hadoop YARN ResourceManager 3.4.1.200-dep-1000 API)

```
public class DecommissioningNodesWatcher
extends java.lang.Object
```
DecommissioningNodesWatcher is used by ResourceTrackerService to track DECOMMISSIONING nodes to decide when, after all running containers on the node have completed, will be transitioned into DECOMMISSIONED state (NodeManager will be told to shutdown). Under MR application, a node, after completes all its containers, may still serve it map output data during the duration of the application for reducers. A fully graceful mechanism would keep such DECOMMISSIONING nodes until all involved applications complete. It could be however undesirable under long-running applications scenario where a bunch of "idle" nodes would stay around for long period of time. DecommissioningNodesWatcher balance such concern with a timeout policy --- a DECOMMISSIONING node will be DECOMMISSIONED no later than DECOMMISSIONING_TIMEOUT regardless of running containers or applications. DecommissioningNodesWatcher basically is no cost when no node is DECOMMISSIONING.

Nested Classes
Modifier and Type	Class	Description
`static class`	`DecommissioningNodesWatcher.DecommissioningNodeStatus`	Status about a specific decommissioning node.

Constructors
Constructor	Description
`DecommissioningNodesWatcher(RMContext rmContext)`

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`DecommissioningNodesWatcher.DecommissioningNodeStatus`	`checkDecommissioningStatus(org.apache.hadoop.yarn.api.records.NodeId nodeId)`
`boolean`	`checkReadyToBeDecommissioned(org.apache.hadoop.yarn.api.records.NodeId nodeId)`
`void`	`init(org.apache.hadoop.conf.Configuration conf)`
`void`	`remove(org.apache.hadoop.yarn.api.records.NodeId nodeId)`
`void`	`stop()`
`void`	`update(RMNode rmNode, org.apache.hadoop.yarn.server.api.records.NodeStatus remoteNodeStatus)`	Update rmNode decommissioning status based on NodeStatus.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

public DecommissioningNodesWatcher(RMContext rmContext)

public void init(org.apache.hadoop.conf.Configuration conf)

public void update(RMNode rmNode,
                   org.apache.hadoop.yarn.server.api.records.NodeStatus remoteNodeStatus)

Update rmNode decommissioning status based on NodeStatus.

public void remove(org.apache.hadoop.yarn.api.records.NodeId nodeId)

public boolean checkReadyToBeDecommissioned(org.apache.hadoop.yarn.api.records.NodeId nodeId)

public DecommissioningNodesWatcher.DecommissioningNodeStatus checkDecommissioningStatus(org.apache.hadoop.yarn.api.records.NodeId nodeId)

Class DecommissioningNodesWatcher