High CPU load on SQL Servers

Owned by Pramuk Shyam Pathy (Unlicensed)
Feb 20, 2015
2 min read

Problem

You may experience high CPU load with recent server and connector updates.

Solution

This is caused as the conference session syncing was changed due to missing data from the LcsCDR database.

Depending on your Server and Connector version, please apply the appropriate fixes.

Connector version 4.1.542

The conference session lookup was changed to a more expensive query to locate all conference sessions (the previous query missed some incomplete sessions in the LcsCDR database). The new query caused high CPU load. You should upgrade your connector to 4.1.559 or newer.

Server version 4.1.8

Connector version 4.1.547

The conference session lookup was reverted to the original query that misses data, but doesn’t use so much CPU. The server implemented a back-fill request to the connector asking for specific conference sessions that have missing data. The connector uses the expensive query to query these specific conference sessions. The server sends the connector a set of session identifiers called Dialog IDs. These are looked up from the Dialogs table in the LcsCDR database. SQL Server is using a lot of CPU to look these up. There is limited throttling behaviour, so high CPU load still occurs.

 

You may be able to mitigate the CPU load by creating the following index (get your DBA to run it):

 

create index IX_Dialogs_ExternalId on LcsCDR.dbo.Dialogs (ExternalId)

 

You should upgrade your connector to 4.1.559 or newer.

 

Server version 4.1.9 and newer

Connector version 4.1.559 and newer

You may be able to mitigate the CPU load by creating the following index (get your DBA to run it):

 

create index IX_Dialogs_ExternalId on LcsCDR.dbo.Dialogs (ExternalId)

 

You can also configure the connector to process these sessions in smaller batches if you like, on the Lync 2010/2013 tab in connector configuration.

-          Specific Conference Session Batch Size (for conference sessions)

-          Specific Voip Call Batch Size (for calls)

 

The connector uses the existing Conference Refresh Time (for conference sessions) and Voip Call Refresh Time (for calls) for delays between each batch. You can increase this time, but be aware it will also increase the delay for each batch of regular archive reading.

If you still having issues with CPU load on SQL databases. Please contact Event Zero Support a support@eventzero.com.   

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