Hadoop - Performance Tuning
A user sets
mapreduce.map.memory.mb=4096 but forgets to update mapreduce.map.java.opts. What issue may occur?A user sets mapreduce.map.memory.mb=4096 but forgets to update mapreduce.map.java.opts. What issue may occur?
medium📝 Debug Q7 of 15
Step-by-Step Solution
Solution:
Step 1: Understand mismatch impact
Container memory is 4096 MB but Java heap size remains default (likely smaller).Step 2: Result of small heap size
Heap too small for task needs can cause crashes or OutOfMemoryError.Final Answer:
Java heap size may be too small causing crashes -> Option AQuick Check:
Update java.opts with container memory changes [OK]
Quick Trick: Always update java.opts when changing container memory [OK]
Common Mistakes:
- Assuming container memory alone controls heap size
- Ignoring java.opts setting
- Expecting no errors without java.opts update
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