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Posted to jira@kafka.apache.org by "Boyang Chen (Jira)" <ji...@apache.org> on 2020/01/02 17:36:00 UTC

[jira] [Commented] (KAFKA-9356) Potential data loss in InMemoryWindowStore and InMemorySessionStore

    [ https://issues.apache.org/jira/browse/KAFKA-9356?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17006972#comment-17006972 ] 

Boyang Chen commented on KAFKA-9356:
------------------------------------

Thanks for the report. For Streams there is only one writer (stream thread) and one reader (IQ) working on the same in-memory store. So a read-write operation should be safe in this case.

cc [~ableegoldman] [~guozhang]

> Potential data loss in InMemoryWindowStore and InMemorySessionStore
> -------------------------------------------------------------------
>
>                 Key: KAFKA-9356
>                 URL: https://issues.apache.org/jira/browse/KAFKA-9356
>             Project: Kafka
>          Issue Type: Bug
>            Reporter: Roman Leventov
>            Priority: Major
>
> {{InMemoryWindowStore.put()}} and {{InMemorySessionStore.put()}} call {{computeIfAbsent()}} method on {{ConcurrentSkipListMap}} objects which opens up possibility for data loss because {{ConcurrentSkipListMap.computeIfAbsent()}} is not an atomic operation.
> Possible fix: replace {{ConcurrentSkipListMaps with synchronized[Sorted, Navigable]Map(new TreeMap<>())}}.
>   



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