SQL Server - Why would my SPID be "SUSPENDED" but not blocked, while creating an index?

Question

I have a SQL 2005 x64 server, and when I attempt to issue some queries against it (for example, when I try to create an index), my SPID goes to "sleeping" immediately, and seems to wait there indefinitely. It's not being blocked (the "BLKBY" column in SP_WHO2 is empty), and the CPU and DiskIO values are very small (under 300 each), and not growing.

What could my query possibly be waiting for? If I do a SELECT * off the table I'm indexing, I get all million rows back within a minute or so, so it's not blocked table access, or even (it seems) table contention.

Any thoughts on other things I could check? Do I just need to give in and restart my SQL instance? :)

DETAILS: I'm running the CREATE INDEX from another tab in SSMS, and it's never returning - it just shows "Executing" and never returns, so I don't think the process has been abandoned.

Answer 1

select * 
from sys.dm_exec_requests r
join sys.dm_os_tasks t on r.session_id = t.session_id
where r.session_id = <spid of create index>;

This will show not only the status of the request, but also all the tasks spawned by the request. An online CREATE INDEX may spawn parallel threads and will suspend itself until they're finish.

Answer 2

The 'Suspended' state can sometimes be misleading. For example, your query could be 'Suspended' while waiting for disk I/O to complete. This can be verified by running the below query, and checking the wait_type column. PAGEIOLATCH_EX indicates that the query is blocked due to waiting for disk I/O. This doesn't mean that the query is not making progress.

See this page for more information about PAGEIOLATCH_EX

And here is the query that returns the aforementioned information

 SELECT qs.percent_complete ,
        qs.session_id ,
        scheduler_id ,
        blocking_session_id ,
        qs.status ,
        command ,
        wait_time ,
        wait_type ,
        last_wait_type ,
        wait_resource ,
        ST.text ,
        host_name ,
        program_name
 FROM   sys.dm_exec_requests qs
        LEFT JOIN sys.dm_exec_sessions es ON ( qs.session_id = es.session_id )
        CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS ST