very high CPU, 0 I/O, no blocking, NULL in wait type? What could be possibly going wrong?

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very high CPU, 0 I/O, no blocking, NULL in wait type? What could be possibly going wrong?

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curious_sqldba

Posted Wednesday, October 31, 2012 10:31 AM

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I have a select query which is in a "hung" state. I checked there is no blocking. From the activity monitor i see that Wait type is NULL. I do see very very high CPU and 0 on I/O. What could be wrong? Any advice?

Post #1379426

Jack Vamvas

Posted Wednesday, October 31, 2012 11:02 AM

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Has this query been regularly as OK? or is it a new query?
Are the statistics up to date?
Have you checked sys.dm_exec_requests for more detailed information?

Jack Vamvas
sqlserver-dba.com

Post #1379449

sanket kokane

Posted Thursday, November 01, 2012 1:44 AM

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can you please post the Query.

is it linked server related query ?

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संकेत कोकणे

Post #1379653

Markus

Posted Friday, November 02, 2012 6:20 AM

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Find out which SPID it is using and do a SP_WHO2 xxx where xxx is the SPID of the running query. Run this a few times to see if the CPU and I/O are increasing.

Also, do an explain plan on it to see if it is using indexes or table scans. Then see if you can add tuning indexes to make it run more efficiently.

Also, change the SELECT statement to SELECT COUNT(1) to see if it will, somewhat quickly tell you how many rows it should return. Does it return 1 row, 500 rows, 20 million....

Other questions....

Has this query run before... on a regular basis... did it run quickly before and all of a sudden gone crazy.

How big is the table(s), are stats up-to-date... could reindexing the tables be an option?

Post #1380317

SQLQuest29

Posted Friday, November 02, 2012 10:58 AM

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sqldba_newbie (10/31/2012)

you can do .. select * from sys.dm_os_waiting_Tasks and join with sys.dm_exec_requests and sys.dm_exec_sessions to see whats going on ..

Also, Adam Mechanic's sp_whoIsActive is another good stuff that will tell u whats going on currently.

without giving more info about your environment and what steps u have taken to troubleshoot, its very difficult to help you.

HTH,
Cheers !

"Never take life too seriously, nobody gets out of it anyways ! BigGrin

When your love and skills unite, expect a masterpiece !"

Post #1380512

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