[JAVA] Reduce heap usage(Phase 2) - memory footprint in AllocationManager.BufferLedger

[asfimport]

Currently we instantiate IdentityHashMap while creating an instance of AllocationManager which is in turn is part of BufferLedger

By default IdentityHashMap allocates an array of 64 objects which is 272 bytes of heap from the start. In reality a lot of ArrowBuf(s) will not need that many entries in the map, since they want share BufferAllocators with many other BufferLedgers.

Suggestion is to come up with different collection to save heap w/o sacrificing much of the performance (if any).

I have a suggestion in mind that I will share via a doc. later today

Reporter: Yuliya Feldman / @yufeldman
Assignee: Yuliya Feldman / @yufeldman

Related issues:

• [JAVA] Reduce Heap Usage per Vector (blocks)

PRs and other links:

• GitHub Pull Request #1150
• GitHub Pull Request #1150

_{Note: This issue was originally created as ARROW-1627. Please see the migration documentation for further details.}

[asfimport]

Yuliya Feldman / @yufeldman:
Here is the link to proposal on how to deal with the issue: https://docs.google.com/document/d/1pIrPgtwGxMBq-dRzhA-BKDB7KdS2crkTZI21gU-4KDQ/edit?usp=sharing

Will submit PR shortly

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 1150
#1150