Chetan Mehrotra created OAK-1726:
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Summary: 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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