[jira] [Commented] (KAFKA-5172) CachingSessionStore doesn't fetchPrevious correctly.

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-5172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15996038#comment-15996038 ] 

ASF GitHub Bot commented on KAFKA-5172:
---------------------------------------

GitHub user KyleWinkelman opened a pull request:

    https://github.com/apache/kafka/pull/2972

    [KAFKA-5172] Fix fetchPrevious to find the correct session.

    Change fetchPrevious to use findSessions with the proper key and timestamps rather than using fetch.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/KyleWinkelman/kafka CachingSessionStore-fetchPrevious

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/kafka/pull/2972.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #2972
    
----
commit c09a1ace192877ef9f633e14288b680f374b3792
Author: Kyle Winkelman <ky...@optum.com>
Date:   2017-05-04T02:03:50Z

    Fix fetchPrevious to find the correct session.

----


> CachingSessionStore doesn't fetchPrevious correctly.
> ----------------------------------------------------
>
>                 Key: KAFKA-5172
>                 URL: https://issues.apache.org/jira/browse/KAFKA-5172
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>            Reporter: Kyle Winkelman
>
> When using KStreamSessionWindowAggregate by calling KGroupedStream#aggregate() a CachingSessionStore is created.
> This causes the following chain of method calls when a new record that requires removing others from the store appear:
> KStreamSessionWindowAggregate
> CachingSessionStore.remove(Windowed<K>)
> CachingSessionStore.put(Windowed<K>, V)
> ThreadCache.put(String, Bytes *containing Windowed<K> info*, LRUCacheEntry)
> ThreadCache.maybeEvict(String)
> NamedCache.evict()
> NamedCache.flush(LRUNode *containing Bytes and LRUCacheEntry from ThreadCache#put*)
> DirtyEntryFlushListener *defined in CachingSessionStore line 80* .apply(ThreadCache.DirtyEntry *containing Bytes and LRUCacheEntry from ThreadCache#put*)
> CachingSessionStore.putAndMaybeForward(ThreadCache.DirtyEntry *containing Bytes and LRUCacheEntry from ThreadCache#put*, InternalProcessorContext)
> CachingSessionStore.fetchPrevious(Bytes *containing Windowed<K> info*)
> RocksDBSessionStore.fetch(Bytes *containing Windowed<K> info*)
> RocksDBSessionStore.findSessions *on line 48* (Bytes *containing Windowed<K> info*, 0, Long.MAX_VALUE)
> MeteredSegmentedByteStore.fetch(Bytes *containing Windowed<K> info*, 0, Long.MAX_VALUE)
> ChangeLoggingSegmentedByteStore.fetch(Bytes *containing Windowed<K> info*, 0, Long.MAX_VALUE)
> RocksDBSegmentedBytesStore.fetch(Bytes *containing Windowed<K> info*, 0, Long.MAX_VALUE)
> SessionKeySchema.lower/upperRange(Bytes *containing Windowed<K> info*, Long)
> ****** in this method the already Windowed<K> gets Windowed again *****
> The point of showing all this is to point out that the windowed gets windowed and because it passes the 0, Long.MAX_VALUE it searches for a strange key and searches all times for it. I think the fetchPrevious method of CachingSessionStore should be changed to call the byteStores.findSessions(Bytes.wrap(serdes.rawKey(key.key())), key.window().start(), key.window().end()). 



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