[jira] [Commented] (HBASE-22081) master shutdown: close RpcServer first thing, close procWAL as soon as viable, and delete znode the last thing

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

    [ https://issues.apache.org/jira/browse/HBASE-22081?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16802932#comment-16802932 ] 

stack commented on HBASE-22081:
-------------------------------

Sounds good. Reasons for current sequence may not apply anymore. At same time, unfortunately, why it is the way it is may only become apparent when you start messing with it. Thanks [~sershe]

> master shutdown: close RpcServer first thing, close procWAL as soon as viable, and delete znode the last thing
> --------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-22081
>                 URL: https://issues.apache.org/jira/browse/HBASE-22081
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Sergey Shelukhin
>            Priority: Major
>
> I had a master get stuck due to HBASE-22079 and noticed it was logging RS abort messages during shutdown.
> [~bahramch] found some issues where messages are processed by old master during shutdown due to a race condition in RS cache (or it could also happen due to a network race).
> Previously I found some bug where SCP was created during master shutdown that had incorrect state (because some structures already got cleaned).
> I think before master fencing is implemented we can at least make these issues much less likely by thinking about shutdown order.
> 1) First kill RCP server so we don't receive any more messages. There's no need to receive messages when we are shutting down. Server heartbeats could be impacted I guess, but I don't think they will be cause we currently only kill RS on ZK timeout.
> 2) Then do whatever cleanup we think is needed that requires proc wal.
> 3) Then close proc WAL so no errant threads can create more procs.
> 4) Then do whatever other cleanup.
> 5) Finally delete znode.
> Right now znode is deleted somewhat early I think, and RpcServer is closed very late.



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