[SPARK-11271] MapStatus too large for driver

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Component/s: Shuffle, Spark Core
• Assignee: Unassigned
• Reporter: Kent Yao 2
• Created: 23/Oct/15 02:50
• Updated: 17/May/20 18:30
• Resolved: 16/Nov/15 22:56

Description

When I run a spark job contains quite a lot of tasks(in my case is 200k[maptasks]*200k[reducetasks]), the driver occured OOM mainly caused by the object MapStatus,
RoaringBitmap that used to mark which block is empty seems to use too many memories.
I try to use org.apache.spark.util.collection.BitSet instead of RoaringBitMap, and it can save about 20% memories.

For the 200K tasks job,
RoaringBitMap uses 3 Long[1024] and 1 Short[3392] =3*64*1024+16*3392=250880(bit)
BitSet uses 1 Long[3125] = 3125*64=200000(bit)

Memory saved = (250880-200000) / 250880 ≈20%

Issue Links

• is duplicated by: SPARK-11583 Make MapStatus use less memory uage
• links to: [Github] Pull Request #9243 (viirya)