[IMPALA-7219] 7.5% of Catalog Server heap wasted by empty HashMaps and ArrayLists

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: Catalog
• Epic Color: ghx-label-2
• Assignee: Unassigned
• Reporter: Misha Dmitriev
• Created: 28/Jun/18 22:56
• Updated: 21/Dec/20 17:29

Description

I recently analyzed a ~16GB heap dump of Catalog Server with jxray (www.jxray.com). It turns out that 7.5% of the heap is wasted by empty HashMap and ArrayList instances.

These objects come from just four data fields in two classes: IncompleteTable and StructType. It should be easy to get rid of the overhead of these objects by initializing them lazily.