[jira] [Commented] (HBASE-20828) Finish-up AMv2 Design/List of Tenets/Specification of operation

["stack (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-20828?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16612522#comment-16612522 ] 

stack commented on HBASE-20828:
-------------------------------

How to address the issue where a STUCK procedure holds up free-up of master proc WALs? If a Master crash, replaying all edits though most may belong to finished procedures, can keep the  Master occupied for a good amount of time reconstructing in-memory AMv2 state. Chatting w/ Duo, could we do a Procedure Store that was region based? What would it take? What would the model look like? It would at a minimum purge one of the three methods of writing WALs in HDFS that we currently have (MasterProcWAL has its own way of doing appends). TODO.

> Finish-up AMv2 Design/List of Tenets/Specification of operation
> ---------------------------------------------------------------
>
>                 Key: HBASE-20828
>                 URL: https://issues.apache.org/jira/browse/HBASE-20828
>             Project: HBase
>          Issue Type: Umbrella
>          Components: amv2
>            Reporter: stack
>            Priority: Major
>
> AMv2 is missing specification. There are too many grey-areas still. Also missing are a concise listing of the tenets of AMv2 operation. Here are some examples:
>  * HBASE-19529 "Handle null states in AM": Asks how we should treat null state in hbase:meta. What does it 'mean'. We seem to treat it differently dependent on context. Needs clarification. [~Apache9] recently asked similar about the meaning of OFFLINE.
>  * Logging needs to have a particular form to help trace Procedure progress; needs a write-up.
> Lets fill in items to address in this umbrella issue. Can address in subissues and produce specification doc too. We have the below but these are mostly (incomplete) description for devs on pv2 and amv2; the specification is missing:
> http://hbase.apache.org/book.html#pv2
> http://hbase.apache.org/book.html#amv2
> (Other areas include addressing what is up w/ rollback -- when, how much, and when it is not appropriate -- as well as recommendation on Procedures coarseness, locking -- is it ok to lock table in alter table procedure for the life of the procedure? -- and so on).



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