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https://issues.apache.org/jira/browse/KAFKA-15481?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17770830#comment-17770830
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Arpit Goyal commented on KAFKA-15481:
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[~divijvaidya] [~showuon]
1\ we want to ensure here is that removing the entry from cache and renaming
the file to add "delete" suffix should be atomic operations OR
2\ we can add a UUID at the end of each index file downloaded from remote for
this cache so that each "entry" in the cache has a unique file associated with
it.
Should we go with the first or the 2nd approach , IMO 2nd would decouple the
flow and would be simple to understand ?
> Concurrency bug in RemoteIndexCache leads to IOException
> --------------------------------------------------------
>
> Key: KAFKA-15481
> URL: https://issues.apache.org/jira/browse/KAFKA-15481
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 3.6.0
> Reporter: Divij Vaidya
> Priority: Major
> Fix For: 3.7.0
>
>
> RemoteIndexCache has a concurrency bug which leads to IOException while
> fetching data from remote tier.
> Below events in order of timeline -
> Thread 1 (cache thread): invalidates the entry, removalListener is invoked
> async, so the files have not been renamed to "deleted" suffix yet.
> Thread 2: (fetch thread): tries to find entry in cache, doesn't find it
> because it has been removed by 1, fetches the entry from S3, writes it to
> existing file (using replace existing)
> Thread 1: async removalListener is invoked, acquires a lock on old entry
> (which has been removed from cache), it renames the file to "deleted" and
> starts deleting it
> Thread 2: Tries to create in-memory/mmapped index, but doesn't find the file
> and hence, creates a new file of size 2GB in AbstractIndex constructor. JVM
> returns an error as it won't allow creation of 2GB random access file.
> *Potential Fix*
> Use EvictionListener instead of RemovalListener in Caffeine cache as per the
> documentation:
> {quote} When the operation must be performed synchronously with eviction, use
> {{Caffeine.evictionListener(RemovalListener)}} instead. This listener will
> only be notified when {{RemovalCause.wasEvicted()}} is true. For an explicit
> removal, {{Cache.asMap()}} offers compute methods that are performed
> atomically.{quote}
> This will ensure that removal from cache and marking the file with delete
> suffix is synchronously done, hence the above race condition will not occur.
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