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From "Daniel John Debrunner (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2107) Move page latching out of the lock manager
Date Thu, 14 Dec 2006 20:08:23 GMT
    [ http://issues.apache.org/jira/browse/DERBY-2107?page=comments#action_12458593 ] 
            
Daniel John Debrunner commented on DERBY-2107:
----------------------------------------------

Even though the parameters have changed for LockingPolicy.lockRecordForRead its description
has not, nor in any of its implementations. Since you have been working in the code and understanding
it, it would be good to record knowledge you gained, and improve the java doc comments if
they are wrong.

I think this comment for LockingPoliy.lockRecordForRead needs to be augmented (& I think
this is an existing problem ).
  "Lock a record while holding a page latch."
I think the api should state that the latch might be dropped and re-acquired during this call.

The ordering & timing of latching/locking has changed in the row locking implementations
of LockingPolicy.lockRecordForRead.
Can you share with the list any evaluation you perfomed of the effect on this, in terms of
race conditions between multiple threads?





> Move page latching out of the lock manager
> ------------------------------------------
>
>                 Key: DERBY-2107
>                 URL: http://issues.apache.org/jira/browse/DERBY-2107
>             Project: Derby
>          Issue Type: Improvement
>          Components: Store, Services, Performance
>    Affects Versions: 10.3.0.0
>            Reporter: Knut Anders Hatlen
>         Assigned To: Knut Anders Hatlen
>            Priority: Minor
>         Attachments: derby-2107-1a.diff, derby-2107-1a.stat, derby-2107-1b.diff
>
>
> Latching of pages could be done more efficiently locally in store than in the lock manager.
See the discussion here: http://thread.gmane.org/gmane.comp.apache.db.derby.devel/33135

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