Duplicate resource on deadlock xml

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The question:

As I was debugging a deadlock, I noticed that in the xml’s resource-list, the first and third object locks are the same. Is there some reason for this?

The <resource-list> verbatim:

 <resource-list>
  <objectlock lockPartition="0" objid="580509447" subresource="FULL" dbid="7" objectname="censoredV2.dbo.pt_sales" id="lock1929b2d5500" mode="Sch-M" associatedObjectId="580509447">
   <owner-list>
    <owner id="process194df0e5468" mode="Sch-M" />
   </owner-list>
   <waiter-list>
    <waiter id="process1947a066ca8" mode="Sch-M" requestType="wait" />
   </waiter-list>
  </objectlock>
  <objectlock lockPartition="0" objid="94623380" subresource="FULL" dbid="7" objectname="censoredV2.dbo.pt" id="lock1929a8cf480" mode="IX" associatedObjectId="94623380">
   <owner-list>
    <owner id="process1907da684e8" mode="IX" />
   </owner-list>
   <waiter-list>
    <waiter id="process194df0e5468" mode="Sch-M" requestType="wait" />
   </waiter-list>
  </objectlock>
  <objectlock lockPartition="0" objid="580509447" subresource="FULL" dbid="7" objectname="censoredV2.dbo.pt_sales" id="lock1929b2d5500" mode="Sch-M" associatedObjectId="580509447">
   <owner-list>
    <owner id="process1947a066ca8" mode="Sch-M" requestType="wait" />
   </owner-list>
   <waiter-list>
    <waiter id="process1907da684e8" mode="IX" requestType="wait" />
   </waiter-list>
  </objectlock>
 </resource-list>

The Solutions:

Below are the methods you can try. The first solution is probably the best. Try others if the first one doesn’t work. Senior developers aren’t just copying/pasting – they read the methods carefully & apply them wisely to each case.

Method 1

It is not the same. If you look at it more closely the “owner id” is different.
This is ‘Schema Modification’ lock. SQL Server only allows one schema modification lock.

On the first one it is owned by process194df0e5468 and it is granted.
On the third one, it is requested by process1947a066ca8 and waiting, since the first one already has the lock.

This is nice reading about this lock by Michael J.Swart.


All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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