How Hadoop YARN allocates resources to applications and check how much resources are allocated


YARN is a module that manages resources of a Hadoop cluster and schedules.

How Hadoop YARN allocates resources to applications

Once ResourceManager (RM) receives an application from a client, it launches ApplicationMaster (AM) and passes information for executing the application. ApplicationMaster asks ResourceManager for allocating resources. After allocated, next it communicates with NodeManagers (NMs) running on each node, and then starts containers and runs the application.

The Scheduler which allocates resources in Hadoop YARN, and Dominant Resource Fairness (DRF) - sambaiz-net

Events such as resource allocated are notified to ApplicationMaster through AMRMClientAsync.CallbackHandler called by ResourceManager. Similarly, events such as container starting and stopping are notified through NMClientAsync.CallbackHandler called by NodeManagers.

Check how much resources are allocated

yarn command is available.

# aws emr add-steps --cluster-id $CLUSTER_ID --steps Type=Spark,Name="Spark Program",ActionOnFailure=CONTINUE,Args=[--class,org.apache.spark.examples.SparkPi,/usr/lib/spark/examples/jars/spark-examples.jar,10]
$ yarn application -list
Total number of applications (application-types: [], states: [SUBMITTED, ACCEPTED, RUNNING] and tags: []):1
                Application-Id      Application-Name        Application-Type          User           Queue                   State             Final-State             Progress                        Tracking-URL
application_1669193308183_0002              Spark Pi                   SPARK        hadoop         default                ACCEPTED               UNDEFINED                   0%                                 N/A

$ yarn application -status application_1669193308183_0002
Application Report : 
        Application-Id : application_1669193308183_0002
        Application-Name : Spark Pi
        Application-Type : SPARK
        User : hadoop
        Queue : default
        Application Priority : 0
        Start-Time : 1669193960802
        Finish-Time : 1669193970732
        Progress : 100%
        State : FINISHED
        Final-State : SUCCEEDED
        Tracking-URL : ip-172-31-33-99.ap-northeast-1.compute.internal:18080/history/application_1669193308183_0002/1
        RPC Port : -1
        AM Host :
        Aggregate Resource Allocation : 61411 MB-seconds, 14 vcore-seconds
        Aggregate Resource Preempted : 0 MB-seconds, 0 vcore-seconds
        Log Aggregation Status : SUCCEEDED
        Diagnostics : 
        Unmanaged Application : false
        Application Node Label Expression : <Not set>
        AM container Node Label Expression : <DEFAULT_PARTITION>
        TimeoutType : LIFETIME  ExpiryTime : UNLIMITED  RemainingTime : -1seconds

$ yarn top
YARN top - 09:07:05, up 0d, 0:18, 0 active users, queue(s): root
NodeManager(s): 1 total, 1 active, 0 unhealthy, 1 decommissioned, 0 lost, 0 rebooted
Queue(s) Applications: 1 running, 3 submitted, 0 pending, 2 completed, 0 killed, 0 failed
Queue(s) Mem(GB): 10 available, 0 allocated, 0 pending, 0 reserved
Queue(s) VCores: 3 available, 1 allocated, 0 pending, 0 reserved
Queue(s) Containers: 1 allocated, 0 pending, 0 reserved

                  APPLICATIONID USER             TYPE      QUEUE PRIOR   #CONT  #RCONT  VCORES RVCORES     MEM    RMEM  VCORESECS    MEMSECS %PROGR       TIME NAME                                                                               
 application_1669193308183_0003 hadoop          spark    default     0       1       0       1       0      0G      0G          0          0   0.00   00:00:00 Spark Pi

It can also check allocated resources each node.

$ yarn node -list -showDetails
Total Nodes:1
         Node-Id             Node-State Node-Http-Address       Number-of-Running-Containers
ip-172-31-39-48.ap-northeast-1.compute.internal:8041            RUNNING ip-172-31-39-48.ap-northeast-1.compute.internal:8042                               2
Detailed Node Information :
        Configured Resources : <memory:11712, vCores:4>
        Allocated Resources : <memory:11712, vCores:2>
        Resource Utilization by Node : PMem:2672 MB, VMem:2672 MB, VCores:1.7560812
        Resource Utilization by Containers : PMem:275 MB, VMem:2054 MB, VCores:1.74
        Node-Labels :