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Posted to dev@lucene.apache.org by "Shai Erera (JIRA)" <ji...@apache.org> on 2010/08/10 12:38:15 UTC
[jira] Updated: (LUCENE-2592) Add static readSnapshotsInfo to
PersistentSnapshotDeletionPolicy
[ https://issues.apache.org/jira/browse/LUCENE-2592?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Shai Erera updated LUCENE-2592:
-------------------------------
Attachment: LUCENE-2592.patch
Patch adds readSnapshotsInfo as well as a test case.
> Add static readSnapshotsInfo to PersistentSnapshotDeletionPolicy
> ----------------------------------------------------------------
>
> Key: LUCENE-2592
> URL: https://issues.apache.org/jira/browse/LUCENE-2592
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Reporter: Shai Erera
> Assignee: Shai Erera
> Priority: Minor
> Fix For: 3.1, 4.0
>
> Attachments: LUCENE-2592.patch
>
>
> PSDP persists the snapshots information in a Directory. When you open PSDP, it obtains a write lock on the snapshots dir (by keeping an open IndexWriter), and updates the directory when snapshots are created/released.
> This causes problem in the following scenario -- you have two processes, one updates the 'content' index and keeps PSDP open (because it also takes snapshots). Another process wants to read the existing snapshots information and open a read-only IndexReader on the 'content' index. The other process cannot read the existing snapshots information, because p1 keeps a write lock on the snapshots directory.
> There are two possible solutions:
> # Have PSDP open the IndexWriter over the directory for each snapshot/release. A bit expensive, and unnecessary.
> # Introduce a static readSnapshotsInfo on PSDP which accepts a Directory and returns the snapshots information. IMO it's cleaner, and won't have the performance overhead of opening/closing the IW as before.
> I'll post a patch (implementing the 2nd approach) shortly. I'd appreciate any comments.
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