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https://issues.apache.org/jira/browse/KAFKA-5172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15996038#comment-15996038
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ASF GitHub Bot commented on KAFKA-5172:
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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
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)
> CachingSessionStore.put(Windowed, V)
> ThreadCache.put(String, Bytes *containing Windowed 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 info*)
> RocksDBSessionStore.fetch(Bytes *containing Windowed info*)
> RocksDBSessionStore.findSessions *on line 48* (Bytes *containing Windowed
> info*, 0, Long.MAX_VALUE)
> MeteredSegmentedByteStore.fetch(Bytes *containing Windowed info*, 0,
> Long.MAX_VALUE)
> ChangeLoggingSegmentedByteStore.fetch(Bytes *containing Windowed info*, 0,
> Long.MAX_VALUE)
> RocksDBSegmentedBytesStore.fetch(Bytes *containing Windowed info*, 0,
> Long.MAX_VALUE)
> SessionKeySchema.lower/upperRange(Bytes *containing Windowed info*, Long)
> ** in this method the already Windowed 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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