[HBASE-23258] Reconsider the DBB memory leak in the exceptional paths.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Assignee: Zheng Hu
• Reporter: Zheng Hu
• Created: 06/Nov/19 05:31
• Updated: 26/Mar/20 19:52
• Resolved: 26/Mar/20 19:52

Description

Have a discussion with Anoop Sam John, we find still have some exceptional paths which we did not handle DBB#release correctly. More details are the following:

> HFileReaderImpl#validateBlockType - When throws Exception, the get block is gone. Want to return?
Yeah, we've two cases to validateBlockType. one is reading from cache, another one is reading from hfile. 
we've abstracted the block for both cache types and hfiles ( ex release the block from heap will donothing), so
here seems we should do release if throws IOException.

> Only inside another condition we return and evict block
readBlock - The got block is unused when we throw Exception on DBE type mismatch
Em..we return null finally , seems the block also need to release the block.

Will take a look around all the exceptional paths and consider any other DBB leak issues.

Issue Links

• is related to: HBASE-22480 Get block from BlockCache once and return this block to BlockCache twice make ref count error.