AssemblyVersion: 5.2.0
PortalID: -1
PortalName:
UserID: -1
UserName:
ActiveTabID: -1
ActiveTabName:
RawURL:
AbsoluteURL:
AbsoluteURLReferrer:
UserAgent:
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 90eeea29-5ec2-420e-a822-7de57d76cfd2
InnerException: This operation returned because the timeout period expired. (Exception from HRESULT: 0x800705B4)
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.Threading.ReaderWriterLock.AcquireWriterLockInternal
StackTrace:
Message: System.ApplicationException: This operation returned because the timeout period expired. (Exception from HRESULT: 0x800705B4) at System.Threading.ReaderWriterLock.AcquireWriterLockInternal(Int32 millisecondsTimeout) at DotNetNuke.Services.Scheduling.DNNScheduling.Scheduler.CoreScheduler.RemoveFromScheduleInProgress(ScheduleItem objScheduleItem)
Source:
Server Name: WEB22

Any thoughts on the cause?  It seems to be new after upgrade to DNN 5.2

There are other things in SQL that can cause timeouts.   Lousy front end code or bad sql are two.

Assuming transactions logs, memory, cpu and processes are normal and this issue continues what else would you recommend?  

DNN is technically a vendor type system, and is managed all from from the front end.   

What about SchedulerHistory, could excessive row counts cause this?   (say, over 100000 rows?)

I am also getting this error i just upgraded to dnn 5.2 my  schedule history is fine what else could i check?