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https://issues.apache.org/jira/browse/CASSANDRA-10726?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16585612#comment-16585612
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Alex Petrov commented on CASSANDRA-10726:
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Thank you!
A couple more nits:
*
[here|https://github.com/bdeggleston/cassandra/commit/7b753828e38bb92884219867e10d01e4f4184da6#diff-b677a5a6a3f1a90a889bcf906c1f8001R56]
here switch to {{ConcurrentMap}} seems to be unnecessary. If it's for explicit
contract, I don't mind to leave it.
*
[here|https://github.com/bdeggleston/cassandra/commit/7b753828e38bb92884219867e10d01e4f4184da6#diff-0246c72855070863c2fdbee6d97f494dR156]
we break unconditionally, so we might want to remove loop. I realise that the
collection might be empty though, in which case this might be justified.
*
[here|https://github.com/bdeggleston/cassandra/commit/7b753828e38bb92884219867e10d01e4f4184da6#diff-0246c72855070863c2fdbee6d97f494dR170]
I'm not 100% on board with rename as we're delegating the call to
{{repair.maybeSendAdditionalRepairs}}, I think renaming {{awaitReads}} was
enough. Or, if writes here are meant in the context of repair anyways, we
should rename delegated method. Whichever way you might prefer.
> Read repair inserts should not be blocking
> ------------------------------------------
>
> Key: CASSANDRA-10726
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10726
> Project: Cassandra
> Issue Type: Improvement
> Components: Coordination
> Reporter: Richard Low
> Assignee: Blake Eggleston
> Priority: Major
> Fix For: 4.x
>
>
> Today, if there’s a digest mismatch in a foreground read repair, the insert
> to update out of date replicas is blocking. This means, if it fails, the read
> fails with a timeout. If a node is dropping writes (maybe it is overloaded or
> the mutation stage is backed up for some other reason), all reads to a
> replica set could fail. Further, replicas dropping writes get more out of
> sync so will require more read repair.
> The comment on the code for why the writes are blocking is:
> {code}
> // wait for the repair writes to be acknowledged, to minimize impact on any
> replica that's
> // behind on writes in case the out-of-sync row is read multiple times in
> quick succession
> {code}
> but the bad side effect is that reads timeout. Either the writes should not
> be blocking or we should return success for the read even if the write times
> out.
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