"Non-yielding Scheduler" error is logged in the SQL Server 2008 or SQL Server 2008 R2 error log f (4240786)

During a Litespeed backup or restore the application or even SQL Server may hang.

You receive a "Non-yielding Scheduler" error intermittently.

In the SQL Server error logs you may see the following error messages:

Process %ld:%ld:%ld (0x%lx) Worker 0x%p appears to be non-yielding on Scheduler %ld. Thread creation time: %time. Approx Thread CPU Used: kernel 0x ms, user 0x ms. Process Utilization 0x%. System Idle 0x%. Interval: 0x ms.

Or

error code 26073 - // ErrorFormat: TCP connection closed but a child process of SQL Server may be holding a duplicate of the connection's socket

This issue occurs because SQL Server Native Client 10.0 handles a TCP close call on a socket incorrectly.

When a child process is created from sqlservr.exe within a very precise timing window around a new connection arriving, SQL Server 2008 or 2008 R2 errors in how it is managing its own resources. This may create SQL Server errors. Please refer to Microsoft KB 2491214 for more information: http://support.microsoft.com/kb/2491214

WORKAROUND 1:

Install SQL Server 2008 R2 CU6 (available in KB 2491214 mentioned above)

WORKAROUND 2:

Install SQL Server 2008 R2 Service Pack 1 http://www.microsoft.com/download/en/details.aspx?id=26727

WORKAROUND 3:

If for whatever reason you do not wish to install either of those updates in options 1) or 2), an alternative workaround would be to make a registry configuration change to the MSSQLServer registry key value SuperSocketNetlib\Tcp\TcpAbortiveClose as mentioned in the Microsoft Knowledge Base article mentioned above. As always, use great care when editing the registry.

Additional Information:

If you need help in determining which option is best suited for your environment to resolve this issue, please contact Quest Support for further assistance.

Environment: SQL Server 2008, SQL Server 2008 R2, Windows Server 2008, Windows Server 2008 R2