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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HBASE-18027) HBaseInterClusterReplicationEndpoint should respect RPC size limits when batching edits
Date Sat, 13 May 2017 15:52:04 GMT

    [ https://issues.apache.org/jira/browse/HBASE-18027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16009381#comment-16009381
] 

Andrew Purtell edited comment on HBASE-18027 at 5/13/17 3:51 PM:
-----------------------------------------------------------------

[~lhofhansl] The worklist handed to HICRE#Replicator can exceed the RPC limit so we break
it into separate RPCs if we need to. I think that's the best place to do it, since it is the
code that is directly involved with creating the RPCs. The replication batch limit and the
RPC size limits can be set in a way that accidentally conflict, so we need to do this check
at the last step. The code in ReplicationSourceWorkerThread.readAllEntriesToReplicateOrNextFile
can generate an overly large worklist because the size check occurs after the current entry
(which can put it over limit) is added to the list. This can be changed but I still contend
the best place to check where we are exceeding RPC limits is where we are generating the RPCs.



was (Author: apurtell):
[~lhofhansl] The worklist handed to HICRE#Replicator can exceed the RPC limit so we break
it into separate RPCs if we need to. I think that's the best place to do it, since it is the
code that is directly involved with creating the RPCs. The replication batch limit and the
RPC size limits can be set in a way that accidentally conflict, so we need to do this check
at the last step. 

> HBaseInterClusterReplicationEndpoint should respect RPC size limits when batching edits
> ---------------------------------------------------------------------------------------
>
>                 Key: HBASE-18027
>                 URL: https://issues.apache.org/jira/browse/HBASE-18027
>             Project: HBase
>          Issue Type: Bug
>          Components: Replication
>    Affects Versions: 2.0.0, 1.4.0, 1.3.1
>            Reporter: Andrew Purtell
>            Assignee: Andrew Purtell
>             Fix For: 2.0.0, 1.4.0, 1.3.2
>
>         Attachments: HBASE-18027-branch-1.patch, HBASE-18027.patch, HBASE-18027.patch
>
>
> In HBaseInterClusterReplicationEndpoint#replicate we try to replicate in batches. We
create N lists. N is the minimum of configured replicator threads, number of 100-waledit batches,
or number of current sinks. Every pending entry in the replication context is then placed
in order by hash of encoded region name into one of these N lists. Each of the N lists is
then sent all at once in one replication RPC. We do not test if the sum of data in each N
list will exceed RPC size limits. This code presumes each individual edit is reasonably small.
Not checking for aggregate size while assembling the lists into RPCs is an oversight and can
lead to replication failure when that assumption is violated.
> We can fix this by generating as many replication RPC calls as we need to drain a list,
keeping each RPC under limit, instead of assuming the whole list will fit in one.



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