[OAK-2808] Active deletion of 'deleted' Lucene index files from DataStore without relying on full scale Blob GC

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.7.1, 1.8.0
• Component/s: lucene
• Labels: datastore doc-impacting performance
• Epic Link: indexer resilience
• Assignee: Vikas Saurabh
• Reporter: Chetan Mehrotra
• Created: 24/Apr/15 15:17
• Updated: 08/Oct/19 15:22
• Resolved: 06/Jun/17 07:43

Description

With storing of Lucene index files within DataStore our usage pattern
of DataStore has changed between JR2 and Oak.

With JR2 the writes were mostly application based i.e. if application
stores a pdf/image file then that would be stored in DataStore. JR2 by
default would not write stuff to DataStore. Further in deployment
where large number of binary content is present then systems tend to
share the DataStore to avoid duplication of storage. In such cases
running Blob GC is a non trivial task as it involves a manual step and
coordination across multiple deployments. Due to this systems tend to
delay frequency of GC

Now with Oak apart from application the Oak system itself actively
uses the DataStore to store the index files for Lucene and there the
churn might be much higher i.e. frequency of creation and deletion of
index file is lot higher. This would accelerate the rate of garbage
generation and thus put lot more pressure on the DataStore storage
requirements.

Discussion thread http://markmail.org/thread/iybd3eq2bh372zrl

Issue Links

• breaks: OAK-6314 ActiveDeletedBlobCollectorTest.multiThreadedCommits is failing intermittently for a few users
• breaks: OAK-6503 Active deletion of blobs tries to delete sub-16k inlined blobs in case of seg-tar
• breaks: OAK-6504 Active deletion of blobs needs to indicate information about purged blobs to mark-sweep collector
• is related to: OAK-6950 Active deletion can delete blobs from a shared datastore when a clone setup is created
• is related to: OAK-3140 DataStore / BlobStore: add a method to pass a "type" when writing
• is related to: OAK-4200 [BlobGC] Improve collection times of blobs available
• is related to: OAK-5192 Reduce Lucene related growth of repository size
• is related to: OAK-6269 Support non chunk storage in OakDirectory
• is related to: OAK-6337 Decide major version bump of o.a.j.o.api.jmx
• is required by: OAK-6334 ActiveDeletedBlobCollectorFactory has lots of inner classes. Refactor it to be more modular and testable
• relates to: OAK-3536 Indexing with Lucene and copy-on-read generate too much garbage in the BlobStore
• relates to: OAK-6862 Active deletion of Lucene binaries: JMX bean, and ability to disable automatic
• relates to: OAK-7968 Active deletion of Lucene binaries: configuration option to disable