Report Server Subscription never completes Warning about subscriptions processing may be delayed

[micheledubose]

Hello,

I've created a subscription on my Report Server and when I run it, it stays on "Pending".  I've checked the app logs and noticed this:

WARN: Schedules, events, and subscriptions processing may be delayed because processing queue reached the maximum item count = 4. Items currently being processed: #0, Microsoft.ReportingServices.Library.NotificationQueueItem #1, Microsoft.ReportingServices.Library.NotificationQueueItem #2, Microsoft.ReportingServices.Library.NotificationQueueItem #3, Microsoft.ReportingServices.Library.NotificationQueueItem.

I've also checked the database ReportServer Notifications table and information is returned.  From researching this warning, I've found that a fix is to set the MaxQueueThreads value other than 0.  MaxQueueThreads specifies the number of threads used by the Report Server Windows service for concurrent processing of subscriptions and notifications.  I do not understand what this property has to do with the warning in my case. I do not have concurrent subscriptions running so why would I get this warning? Also, is there a negative impact with changing the MaxQueueThreads?

[micheledubose · Accepted solution]

It appears that the issue was caused by the paginaed report name containing special characters. According to Microsoft, this is a known issue.  To resolve, I've reapplied the service account credentials in the Report Manager that points to the Report Server and ReportServerTempDB databases.

[Icey]

Hi @micheledubose ,

In general, the warning will not affect the process. It can be overlooked. And it is not suggested to change the MaxQueueThreads value. Here is one explaination for MaxQueueThreads: 

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As we can read, the MaxQueueThreads element in the RSreportserver.config file specifies the number of threads used by the Report Server Windows service for concurrent processing of subscriptions and notifications. For example, there are 10 subscriptions pending and we set the MaxQueueThreads to 1, then the Reporting Services will start all of the 10 subscriptions at the specified time but it will make sure that only 1 subscription thread is running at one time. When it finishes, then another one of the subscriptions will start up. Becasue all of these subscription threads running the same subscription stored procedures, the running subscription puts locks on the Notification and Subscription tables thus blocking other subscription calls.

By default, the MaxQueueThreads is set to 0. In this condition, the value will be calculated using the formula: 2 * number of CPUs. For example, if we have 2 CPUs and set the MaxQueueThreads to 0, the actual value of MaxQueueThreads is 4. And we can set the MaxQueueThreads to a bigger value such as 6. Sorry that I am not clear about the maximum valid value for each CPU.

In this issue, you can test the impact that changing the value of the MaxQueueThreads to a larger value based on your environment. Too high a value might cause a negative impact because even if we have more parallel threads, in reality we have only one thread running per CPU at given time.

Reference:  What steps can be taken to improve the performance of Data Driven Subscriptions (MaxQueueThreads) ? ...

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In addition, does the subscription finally run successfully? And are there any complex calculations in your report? It may cause the "Pending" status. Please check the performace of your Report Server report. And you can also try to allocate more memory to Report Server: Configure Available Memory for Report Server Applications - SQL Server Reporting Services (SSRS) | M....

Best Regards,

Icey

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[micheledubose]

Hi @Icey,

The reports are still showing as pending or processing.  In one of the reports, there isn't any complex calculations. You'd mentioned to ignore the warning but what else could cause the reports to not finished running? 

I'd recently had to restart the Power BI Report Server service, would that have caused this?  Besides possibly adding memory, is there another way to get the reports to finished running?