[jira] [Assigned] (HBASE-26960) Another case for unnecessary replication suspending in RegionReplicationSink

["chenglei (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-26960?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

chenglei reassigned HBASE-26960:
--------------------------------

    Assignee: chenglei

> Another case for unnecessary replication suspending in RegionReplicationSink
> ----------------------------------------------------------------------------
>
>                 Key: HBASE-26960
>                 URL: https://issues.apache.org/jira/browse/HBASE-26960
>             Project: HBase
>          Issue Type: Bug
>          Components: read replicas
>    Affects Versions: 3.0.0-alpha-2
>            Reporter: chenglei
>            Assignee: chenglei
>            Priority: Major
>
> There is another case replication  in {{RegionReplicationSink}} would be suspend:
> For {{RegionReplicationSink}}, when there is a replication error , {{RegionReplicationSink}} invokes {{MemStoreFlusher#requestFlush}} to request a flush, and after receiving the {{FlushAction#START_FLUSH}} or {{FlushAction#CANNOT_FLUSH}} flush marker, it would resume the replication. But when {{MemStoreFlusher}}  flushing, it invokes following method {{HRegion.flushcache}} with the {{writeFlushRequestWalMarker}} set to false:
> {code:java}
>   public FlushResultImpl flushcache(List<byte[]> families,
>       boolean writeFlushRequestWalMarker, FlushLifeCycleTracker tracker) throws IOException {
>  }
> {code}
> When  {{writeFlushRequestWalMarker}} is set to false, {{HRegion.flushcache}} does not write the {{FlushAction#CANNOT_FLUSH}} flush marker to {{WAL}} when the memstore is empty, so when there is a replication error when the memstore is empty(eg. replicating the {{FlushAction#START_FLUSH}}  or {{FlushAction#COMMIT_FLUSH}} ), the replication may suspend until next memstore flush,even though later there are user writes and it could replicate normally.
> I simulate this problem in the PR , and for {{writeFlushRequestWalMarker}} paramter, it is introduced by HBASE-11580 and just only determines whether writing the {{FlushAction#CANNOT_FLUSH}} flush marker to WAL when the memstore is empty, so I think for simplicity, we could set it to true always for {{MemStoreFlusher}}.



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