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https://issues.apache.org/jira/browse/CASSANDRA-10726?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16125586#comment-16125586
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Marcus Eriksson commented on CASSANDRA-10726:
---------------------------------------------
[~xiaolong...@gmail.com] seems we are getting a CME:
{code}
java.util.ConcurrentModificationException: null
at java.util.HashMap$HashIterator.nextNode(HashMap.java:1437)
~[na:1.8.0_149-apple]
at java.util.HashMap$KeyIterator.next(HashMap.java:1461)
~[na:1.8.0_149-apple]
at
org.apache.cassandra.service.DataResolver$RepairMergeListener.awaitRepairResponses(DataResolver.java:298)
~[main/:na]
at
org.apache.cassandra.service.DataResolver$RepairMergeListener.waitRepairToFinishWithPossibleRetry(DataResolver.java:223)
~[main/:na]
at
org.apache.cassandra.service.DataResolver$RepairMergeListener.close(DataResolver.java:175)
~[main/:na]
at
org.apache.cassandra.db.partitions.UnfilteredPartitionIterators$2.close(UnfilteredPartitionIterators.java:175)
~[main/:na]
at
org.apache.cassandra.db.transform.BaseIterator.close(BaseIterator.java:92)
~[main/:na]
at
org.apache.cassandra.service.DataResolver.compareResponses(DataResolver.java:103)
~[main/:na]
at
org.apache.cassandra.service.ReadCallback$AsyncRepairRunner.run(ReadCallback.java:232)
~[main/:na]
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
~[na:1.8.0_149-apple]
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
~[na:1.8.0_149-apple]
at
org.apache.cassandra.concurrent.NamedThreadFactory.lambda$threadLocalDeallocator$0(NamedThreadFactory.java:81)
~[main/:na]
at java.lang.Thread.run(Thread.java:745) ~[na:1.8.0_149-apple]
{code}
in the
{{materialized_views_test.py:TestMaterializedViewsConsistency.multi_partition_consistent_reads_after_write_test}}
dtest
> 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: Xiaolong Jiang
> 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 to update out of date replicas is blocking.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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