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https://issues.apache.org/jira/browse/DERBY-4055?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Knut Anders Hatlen updated DERBY-4055:
--------------------------------------

    Issue & fix info: [High Value Fix, Workaround attached]  (was: [High Value 
Fix])
             Urgency: Normal

Triaged for 10.5.2.

> Space may not be reclaimed if  row locks are not available after three 
> retries 
> -------------------------------------------------------------------------------
>
>                 Key: DERBY-4055
>                 URL: https://issues.apache.org/jira/browse/DERBY-4055
>             Project: Derby
>          Issue Type: Bug
>          Components: Store
>    Affects Versions: 10.1.3.1, 10.2.2.0, 10.3.3.0, 10.4.2.0, 10.5.1.1
>            Reporter: Kathey Marsden
>         Attachments: derby.log.T_RawStoreFactoryWithAssert
>
>
> In a multithreaded clob update where the same row is being updated, space 
> will not be reclaimed.  The offending code is in ReclaimSpaceHelper:
>       RecordHandle headRecord = work.getHeadRowHandle();
>               if (!container_rlock.lockRecordForWrite(
>                 tran, headRecord, false /* not insert */, false /* nowait */))
>               {
>                       // cannot get the row lock, retry
>                       tran.abort();
>                       if (work.incrAttempts() < 3)
>             {
>                               return Serviceable.REQUEUE;
>             }
>                       else
>             {
>                 // If code gets here, the space will be lost forever, and
>                 // can only be reclaimed by a full offline compress of the
>                 // table/index.
>                 if (SanityManager.DEBUG)
>                 {
>                     if (SanityManager.DEBUG_ON(DaemonService.DaemonTrace))
>                     {
>                         SanityManager.DEBUG(
>                             DaemonService.DaemonTrace, 
>                             "  gave up after 3 tries to get row lock " + 
>                             work);
>                     }
>                 }
>                               return Serviceable.DONE;
>             }
>               }
> If we cannot get the lock after three tries we give up.  The reproduction for 
> this issue is in the test 
> store.ClobReclamationTest.xtestMultiThreadUpdateSingleRow().
> This issue also used to reference the code below and has some references to 
> trying to get a reproduction for that issue, but that work has moved to 
> DERBY-4054.  Please see DERBY-4054 for work on the container lock issue.
> ContainerHandle containerHdl = 
>                       openContainerNW(tran, container_rlock, 
> work.getContainerId());
>               if (containerHdl == null)
>               {
>                       tran.abort();
>                       if (SanityManager.DEBUG)
>             {
>                 if (SanityManager.DEBUG_ON(DaemonService.DaemonTrace))
>                 {
>                     SanityManager.DEBUG(
>                         DaemonService.DaemonTrace, " aborted " + work + 
>                         " because container is locked or dropped");
>                 }
>             }
>                       if (work.incrAttempts() < 3) // retry this for serveral 
> times
>             {
>                               return Serviceable.REQUEUE;
>             }
>                       else
>             {
>                 // If code gets here, the space will be lost forever, and
>                 // can only be reclaimed by a full offline compress of the
>                 // table/index.
>                 if (SanityManager.DEBUG)
>                 {
>                     if (SanityManager.DEBUG_ON(DaemonService.DaemonTrace))
>                     {
>                         SanityManager.DEBUG(
>                             DaemonService.DaemonTrace, 
>                             "  gave up after 3 tries to get container lock " 
> + 
>                             work);
>                     }
>                 }
>                               return Serviceable.DONE;
>             }
>               }       

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