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