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https://issues.apache.org/jira/browse/OAK-1726?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13969439#comment-13969439
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Chetan Mehrotra commented on OAK-1726:
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To support this we would need to implement OAK-1667 also as that would help a
DataStore to pre estimate the blob length and determine if the InputStream
should be cached or not
> Improve support for local caching in BlobStore
> ----------------------------------------------
>
> Key: OAK-1726
> URL: https://issues.apache.org/jira/browse/OAK-1726
> Project: Jackrabbit Oak
> Issue Type: Wish
> Components: blob
> Reporter: Chetan Mehrotra
> Assignee: Chetan Mehrotra
>
> As notes in OAK-1702 currently BlobStore and FileDataStore do not perform
> well when large number of small blobs are accessed frequently.
> * FileDataStore - It creates a new instance of LazyInputStream [1] which has
> finalize method implemented (by extending AutoCloseInputStream). This causes
> slow GC [1] when large number of such streams are created. Further reading
> lots of such small blob frequently causes lots of os calls for IO which are
> slow
> * BlobStore - When binary content is stored remotely then accessing it
> frequently would be costly if it is not cached locally
> To better support such access patterns we should have a caching BlobStore for
> reads. At minimum blobs can be cached on heap. However a better approach
> would be to save such blob content in a bigger file and memory map it.
> Possibly using the Segment TarFile. In this mode the blobs would be saved off
> heap and would not put pressure on GC
> [1]
> https://github.com/apache/jackrabbit/blob/trunk/jackrabbit-data/src/main/java/org/apache/jackrabbit/core/data/LazyFileInputStream.java
> [2]
> http://stackoverflow.com/questions/2954948/performance-implications-of-finalizers-on-jvm
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