Container allocation in Hadoop - Step-by-Step Execution

Concept Flow - Container allocation

Job Request Submitted

↓

Resource Manager Receives Request

↓

Check Available Resources

↓

Allocate Container

↓

Launch Task

↓

Task Running

This flow shows how Hadoop's Resource Manager handles a job request by checking resources, allocating containers if available, or waiting if not.

Execution Sample

Hadoop

request = submit_job()
resources = check_resources()
if resources.available():
    container = allocate_container()
    launch_task(container)
else:
    wait_and_retry()

This code simulates requesting a job, checking resources, allocating a container if possible, or waiting to retry.

Execution Table

Step	Action	Resources Available?	Container Allocated	Task Launched	Next Step
1	Submit job request	N/A	No	No	Check resources
2	Check available resources	Yes	No	No	Allocate container
3	Allocate container	Yes	Yes	No	Launch task
4	Launch task in container	Yes	Yes	Yes	Task running
5	Task running	Yes	Yes	Yes	Complete or wait for next job

💡 Task launched successfully; container allocated and running.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
request	None	Job submitted	Job submitted	Job submitted	Job submitted	Job submitted
resources	Unknown	Unknown	Available	Available	Available	Available
container	None	None	None	Allocated	Allocated	Allocated
task_status	Not started	Not started	Not started	Not started	Running	Running

Key Moments - 2 Insights

Why does the system wait instead of allocating a container immediately?

If resources are not available (see Step 2 in execution_table), the system waits to retry allocation later.

What happens after a container is allocated?

After allocation (Step 3), the task is launched inside the container (Step 4), changing task_status to running.

Visual Quiz - 3 Questions

Look at the execution_table at Step 2: Are resources available to allocate a container?

A Yes, resources are available

B No, resources are not available

C Resources status is unknown

D Container already allocated

💡 Hint

Check the 'Resources Available?' column at Step 2 in execution_table

At which step is the task launched inside the container?

A Step 1

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the 'Task Launched' column in execution_table

If resources were not available at Step 2, what would be the next action?

A Allocate container anyway

B Wait and retry allocation

C Launch task without container

D Complete the job immediately

💡 Hint

Refer to the concept_flow where 'No' resources lead to 'Wait in Queue' and retry

Concept Snapshot

Container allocation in Hadoop:
- Job requests sent to Resource Manager
- Resource Manager checks available resources
- If available, container allocated
- Task launched inside container
- If not, job waits and retries allocation

Full Transcript

Container allocation in Hadoop starts when a job request is submitted to the Resource Manager. The manager checks if resources are available. If yes, it allocates a container and launches the task inside it. If resources are not available, the job waits in a queue and retries allocation later. This process ensures tasks run only when resources are free, managing cluster workload efficiently.