[Solved] Given the following configuration:mapreduce.reduce.memory.mb=4096 mapreduce.reduce.java.opts=-Xmx3072mWhat will happen if a reduce task tries to use 3500 MB heap memory? | Hadoop

Hadoop - Performance Tuning

Given the following configuration:

mapreduce.reduce.memory.mb=4096
mapreduce.reduce.java.opts=-Xmx3072m

What will happen if a reduce task tries to use 3500 MB heap memory?

AThe task will run successfully using 3500 MB heap

BThe task will automatically increase container memory

CThe task will fail due to exceeding Java heap size limit

DThe task will fail due to exceeding container memory limit

Step-by-Step Solution

Solution:

Step 1: Compare requested heap with limits
Heap limit is 3072 MB, but task tries 3500 MB, which exceeds Java heap limit (-Xmx). Container memory is 4096 MB, so 3500 MB fits container but exceeds heap limit, causing failure.
Final Answer:
The task will fail due to exceeding Java heap size limit -> Option C
Quick Check:
Heap > Java heap limit = failure [OK]

Quick Trick: Heap usage must not exceed Java heap size (-Xmx) [OK]

Common Mistakes:

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