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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). -- This message was sent by Atlassian JIRA (v7.6.3#76005)