Friday, May 6, 2016

Trace, Trace, Trace - Too Many And SQL Can't Keep Up The Pace!

I recently ran into an issue on a client development (thankfully not production) server where the server was performing very poorly.  We didn't see anything obvious in any of the monitoring detail we had, aside from the fact that our monitoring tools also had issues with how SQL was performing (lots of missing data).

Before the client took the last ditch effort of just restarting SQL Server, I checked traces.  There were 9 user traces collecting a ton of trace events.

I manually killed them all and suddenly performance returned to normal.  Phew!  Crisis averted.

As a follow up from that issue, I created a script that stops and then deletes all user traces.  We are discussing setting up a job to run this script periodically to keep traces at bay and I am educating the group on proper trace discipline (and Extended Events).

-- Turn off (## rows returned) messages

-- Set the stage by declaring working variables

-- Create a temp table to hold the results of the trace detail
Property SMALLINT,

-- Populate the temp table with only user trace data (TraceID 1 is the default system trace)
-- In our environment, TraceID #2 is our monitoring software, so we actually have WHERE TraceID > 2
INSERT INTO #TraceDetail (TraceID, Property, Value)
SELECT * FROM ::fn_trace_getinfo(NULL) WHERE TraceID > 1

-- Check to see if there is anything in the table, and if so, start stopping and killing the traces
WHILE (SELECT COUNT(*) FROM #TraceDetail) > 1
-- Just grab the first ID in the table
SELECT TOP 1 @TraceID = TraceID FROM #TraceDetail
-- Build the command to stop (status = 0) and then delete (status = 2) the trace
SELECT @SQLcmd = 'EXEC sp_trace_setstatus @traceid = ' + CONVERT(VARCHAR(3), @TraceID) + ', @status = 0;
EXEC sp_trace_setstatus @traceid = 'CONVERT(VARCHAR(3), @TraceID) + ', @status = 2;'
-- Execute the command
EXEC (@SQLcmd)
-- Report what we killed
PRINT 'Killed TraceID ' + CONVERT(VARCHAR(3), @TraceID)
-- Delete all entries for that TraceID (typically 5 rows each)
DELETE FROM #TraceDetail WHERE TraceID = @TraceID

-- Drop the temp table
DROP TABLE #TraceDetail