Node label is a way to group nodes with similar characteristics and applications can specify where to run.
Now we only support node partition, which is:
User can specify set of node labels which can be accessed by each queue, one application can only use subset of node labels that can be accessed by the queue which contains the application.
The Node Labels supports the following features for now:
Setup following properties in yarn-site.xml
| Property | Value |
|---|---|
| yarn.node-labels.fs-store.root-dir | hdfs://namenode:port/path/to/store/node-labels/ |
| yarn.node-labels.enabled | true |
Notes:
Add cluster node labels list:
Add labels to nodes
| Property | Value |
|---|---|
| yarn.scheduler.capacity.<queue-path>.capacity | Set the percentage of the queue can access to nodes belong to DEFAULT partition. The sum of DEFAULT capacities for direct children under each parent, must be equal to 100. |
| yarn.scheduler.capacity.<queue-path>.accessible-node-labels | Admin need specify labels can be accessible by each queue, split by comma, like “hbase,storm” means queue can access label hbase and storm. All queues can access to nodes without label, user don’t have to specify that. If user don’t specify this field, it will inherit from its parent. If user want to explicitly specify a queue can only access nodes without labels, just put a space as the value. |
| yarn.scheduler.capacity.<queue-path>.accessible-node-labels.<label>.capacity | Set the percentage of the queue can access to nodes belong to <label> partition . The sum of <label> capacities for direct children under each parent, must be equal to 100. By default, it’s 0. |
| yarn.scheduler.capacity.<queue-path>.accessible-node-labels.<label>.maximum-capacity | Similar to yarn.scheduler.capacity.<queue-path>.maximum-capacity, it is for maximum-capacity for labels of each queue. By default, it’s 100. |
| yarn.scheduler.capacity.<queue-path>.default-node-label-expression | Value like “hbase”, which means: if applications submitted to the queue without specifying node label in their resource requests, it will use “hbase” as default-node-label-expression. By default, this is empty, so application will get containers from nodes without label. |
An example of node label configuration:
Assume we have a queue structure
root
/ | \
engineer sales marketing
We have 5 nodes (hostname=h1..h5) in the cluster, each of them has 24G memory, 24 vcores. 1 among the 5 nodes has GPU (assume it’s h5). So admin added GPU label to h5.
Assume user have a Capacity Scheduler configuration like: (key=value is used here for readability)
yarn.scheduler.capacity.root.queues=engineering,marketing,sales yarn.scheduler.capacity.root.engineering.capacity=33 yarn.scheduler.capacity.root.marketing.capacity=34 yarn.scheduler.capacity.root.sales.capacity=33 yarn.scheduler.capacity.root.engineering.accessible-node-labels=GPU yarn.scheduler.capacity.root.marketing.accessible-node-labels=GPU yarn.scheduler.capacity.root.engineering.accessible-node-labels.GPU.capacity=50 yarn.scheduler.capacity.root.marketing.accessible-node-labels.GPU.capacity=50 yarn.scheduler.capacity.root.engineering.default-node-label-expression=GPU
You can see root.engineering/marketing/sales.capacity=33, so each of them can has guaranteed resource equals to 1/3 of resource without partition. So each of them can use 1/3 resource of h1..h4, which is 24 * 4 * (1/3) = (32G mem, 32 v-cores).
And only engineering/marketing queue has permission to access GPU partition (see root.<queue-name>.accessible-node-labels).
Each of engineering/marketing queue has guaranteed resource equals to 1/2 of resource with partition=GPU. So each of them can use 1/2 resource of h5, which is 24 * 0.5 = (12G mem, 12 v-cores).
Notes:
Applications can use following Java APIs to specify node label to request
Following label-related fields can be seen on web UI: