ResourceManager and NodeManager in Hadoop - Step-by-Step Execution

Concept Flow - ResourceManager and NodeManager

Client submits job

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ResourceManager receives request

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ResourceManager allocates resources

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NodeManager monitors nodes

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NodeManager launches containers

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Containers run tasks

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NodeManager reports status

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ResourceManager updates cluster state

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Job completes or fails

Shows how ResourceManager and NodeManager work together to allocate resources and run tasks in a Hadoop cluster.

Execution Sample

Hadoop

1. Client submits job to ResourceManager
2. ResourceManager allocates containers on NodeManagers
3. NodeManagers launch containers to run tasks
4. NodeManagers report status back to ResourceManager

This sequence shows the interaction between ResourceManager and NodeManagers to run a job.

Execution Table

Step	Action	ResourceManager State	NodeManager State	Output
1	Client submits job	Job queued	Idle	Job accepted
2	ResourceManager allocates containers	Allocating containers	Waiting for launch command	Containers assigned
3	NodeManager launches containers	Containers allocated	Containers launching tasks	Tasks started
4	Tasks running	Monitoring progress	Running tasks	Task progress updates
5	NodeManager reports status	Updating cluster state	Reporting health and progress	Cluster state updated
6	Job completes	Job finished	Idle	Job success notification
7	No more tasks	Idle	Idle	Waiting for next job

💡 Job completes and all tasks finish, ResourceManager and NodeManagers return to idle state

Variable Tracker

Variable	Start	After Step 2	After Step 4	After Step 6
Job Status	None	Queued	Running	Finished
ResourceManager State	Idle	Allocating containers	Monitoring progress	Idle
NodeManager State	Idle	Waiting for launch command	Running tasks	Idle

Key Moments - 2 Insights

Why does ResourceManager allocate containers before NodeManager launches tasks?

ResourceManager decides how many resources (containers) are needed and assigns them to NodeManagers. NodeManagers then launch tasks inside those containers. See execution_table rows 2 and 3.

What happens if a NodeManager fails to report status?

ResourceManager may mark the node as unhealthy and reassign tasks to other nodes. This keeps the cluster stable. This is implied in execution_table row 5 where status updates are crucial.

Visual Quiz - 3 Questions

Look at the execution table, what is the ResourceManager state at Step 4?

A Idle

B Allocating containers

C Monitoring progress

D Job finished

💡 Hint

Check the 'ResourceManager State' column at Step 4 in the execution_table.

At which step does the NodeManager start running tasks?

A Step 3

B Step 5

C Step 2

D Step 6

💡 Hint

Look at the 'NodeManager State' column to see when tasks start running.

If the client submits a new job, what will be the initial ResourceManager state?

A Idle

B Job queued

C Allocating containers

D Monitoring progress

💡 Hint

Refer to Step 1 in the execution_table for ResourceManager state after job submission.

Concept Snapshot

ResourceManager manages resource allocation in the cluster.
NodeManager runs tasks on individual nodes.
Client submits jobs to ResourceManager.
ResourceManager assigns containers to NodeManagers.
NodeManagers launch containers and run tasks.
NodeManagers report status back to ResourceManager.

Full Transcript

This visual execution shows how ResourceManager and NodeManager work together in Hadoop. The client submits a job to ResourceManager, which queues it and allocates containers on NodeManagers. NodeManagers launch containers to run tasks and report their status back. ResourceManager updates cluster state based on these reports. When all tasks finish, the job completes and both ResourceManager and NodeManagers return to idle. Key moments include understanding the allocation of containers before task launch and the importance of NodeManager status reports. The execution table traces each step, showing states and outputs clearly.