[Impala-ASF-CR] IMPALA-7219. Avoid wasting ~160 bytes per IncompleteTable in Catalog Server heap.

["Misha Dmitriev (Code Review)" <ge...@cloudera.org>]

Misha Dmitriev has uploaded a new patch set (#4). ( http://gerrit.cloudera.org:8080/10982 )

Change subject: IMPALA-7219. Avoid wasting ~160 bytes per IncompleteTable in Catalog Server heap.
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IMPALA-7219. Avoid wasting ~160 bytes per IncompleteTable in Catalog Server heap.

This change switches initialization from eager to lazy for the following fields
in Table: HashMap colsByName_ and ArrayType type_. In this way, we
avoid wasting memory when HashMaps stay empty (an empty HashMap still uses at
least 48 bytes in the heap), and when a StructType with its own empty HashMap
and ArrayList instances is initialized, but stays unused. I have calculated
ArrayType, StructType, two HashMaps and one ArrayList collectively use up
160 bytes in the heap per a Table. Further analysis can be found in the JIRA.
This optimization becomes really relevant when a catalog server loads a very
large number (millions) of tables, and all/most of them are represented as
IncompleteTable instances.

Change-Id: If9c75f65ecb3ba3f2c739fa483a84dc052f471c6
---
M fe/src/main/java/org/apache/impala/catalog/Table.java
1 file changed, 24 insertions(+), 4 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/82/10982/4
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: If9c75f65ecb3ba3f2c739fa483a84dc052f471c6
Gerrit-Change-Number: 10982
Gerrit-PatchSet: 4
Gerrit-Owner: Misha Dmitriev <co...@gmail.com>
Gerrit-Reviewer: Misha Dmitriev <co...@gmail.com>
Gerrit-Reviewer: Todd Lipcon <to...@apache.org>
Gerrit-Reviewer: Vuk Ercegovac <ve...@cloudera.com>