DB server CPU 100%

Experts -

The DB server CPU usage hitting 100% sometimes. I do see the some SQL running little longer at these times which runs quicker all the other time. But whenever we reset the WEB server the DB CPU also going down to 20% and stays at 20 for 4-5 hours.

Any idea where to look for the solution?

This is .net /SQL server app.


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strickddConnect With a Mentor Commented:
It sounds like there is a looping/unclosed connection in your code. I would verify that all loops have the connection objects specified and opened OUTSIDE the loop. Then make sure that all your connections have the .Close() method called. Sometimes you may be looping and calling a function that makes a connection so it might not be obvious so track down all the loops and scan all the functions the loops call.

If you don't find any of these then i would take a look at the queries being executed. It could be a deadlock being caused by an overly complex query. Lastly, I would check database triggers and make sure that they are set up properly and not causing issues.
lcohanConnect With a Mentor Database AnalystCommented:
You should also chek your SQL log file for any entries that can lead to the CPU spike. BTW after a web server restart your object/data cache in SQL is also refreshed and maybe you need to look closer at your DB stats/missing indexes and bad query plans stuck in cache.
Anthony PerkinsConnect With a Mentor Commented:
Unfortunately, it sounds like you are sharing the same server for both web server and SQL Server.  This is no recommended, but if you have to do it, you will have to cripple SQL Server by setting the max memory it uses.
sventhanAuthor Commented:
Thanks to you all. The problem is with some SQL (poorly written) update statements. This is getting executed more than wanted. I'm looking into this now.


We have 2 different servers.
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