[HIVE-10068] LLAP: adjust allocation after decompression

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: llap
• Assignee: Unassigned
• Reporter: Sergey Shelukhin
• Created: 24/Mar/15 02:29
• Updated: 18/Nov/15 20:05

Description

We don't know decompressed size of a compression buffer in ORC, all we know is the file-level compression buffer size. For many files, compression buffers can be smaller than that because of compact encoding, or because compression block ends for other reasons (different streams, etc. - "present" streams for example are very small).
BuddyAllocator should be able to accept back parts of the allocated memory (e.g. allocate 256Kb with minimum allocation of 32Kb, decompress 45Kb, return the last 192Kb as 64+128Kb). For generality (this depends on implementation), we can make an API like "offer", and allocator can decide to take back however much it can.