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Posted to oak-issues@jackrabbit.apache.org by "Alex Parvulescu (JIRA)" <ji...@apache.org> on 2014/04/16 20:44:15 UTC
[jira] [Resolved] (OAK-1726) Improve support for local caching in
DataStoreBlobStore
[ https://issues.apache.org/jira/browse/OAK-1726?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Alex Parvulescu resolved OAK-1726.
----------------------------------
Resolution: Fixed
fixed in trunk and merged to 1.0 branch
> Improve support for local caching in DataStoreBlobStore
> -------------------------------------------------------
>
> 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
> Fix For: 1.0
>
> Attachments: OAK-1726-onheap-cache.patch
>
>
> 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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