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https://issues.apache.org/jira/browse/OAK-10494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17775733#comment-17775733
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Axel Hanikel commented on OAK-10494:
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{{getRecordIfStored()}} is called roughly 136000 times per replication package
of 500 paths, so caching 46000 items should be sufficient and 100000 is a safe
bet.
> Cache backend.getRecord() calls to minimise CloudBlob.downloadAttributes()
> over the network
> -------------------------------------------------------------------------------------------
>
> Key: OAK-10494
> URL: https://issues.apache.org/jira/browse/OAK-10494
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: blob-plugins
> Reporter: Axel Hanikel
> Priority: Major
> Attachments: Measurements.md
>
>
> h1. Problem: Metadata are requested more than once for each blob
> Setting a breakpoint in
> {{AbstractSharedCachingDataStore.getRecordIfStored()}} and logging the
> dataIdentifiers, we see that it calls {{backend.getRecord()}} 3 times for the
> same {{dataIdentifier}} when a replication package is installed by vault. The
> reason seems to be that during commits, every {{CommitHook}} runs its own
> {{compareAgainstBaseState}} and, because the implementation avoids fetching
> the blob if it only needs the metadata, the request to the existing blob
> cache is always a miss.
> h1. Proposed solution: Cache {{backend.getRecord()}} calls
> Manual testing has shown that caching {{backend.getRecord()}} calls reduces
> the time spent in {{.getRecordIfStored()}} by between 12 and 35% when
> installing replication packages containing 500 paths.
> The PR is at https://github.com/apache/jackrabbit-oak/pull/1155
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