Continuing the SQLDIY monitoring project we will take a look at tracking blocking events. I actually received a request to update this from a script I had made available at SQLServerCentral. This was a script from the grand old days of SQL Server 2000 and actually used xp_smtp_sendmail That Gert Drapers wrote about a million years ago in SQL Server time. With the advent of database mail it only made sense to update the procedure to use it. This still relies on sysprocesses but since it isn’t deprecated yet I’ve got at least three versions of SQL Server before I need to fix that. I did replace fn_get_sql with sys.dm_exec_sql_text since it is deprecated. Also, it simplified things by reducing the temporary table count by one thanks to the power of cross apply.
This module serves two purposes. One, to alert you based on criteria and thresholds. Two, track blocking issues over time. I found that concurrency issues crop up over time due to increase in data sizes. Tracking these blocking events may help you get in front of what may be a design flaw before it cripples your application.
As always, we create a new table BlockingChains in our local management database.
USE management
GO
DROP TABLE blockingchains
GO
CREATE TABLE [dbo].[BlockingChains]
(
[ServerName] [VARCHAR] (255) NOT NULL,
[SampleTime] [DATETIME] NOT NULL,
[Spid] [INT] NULL,
[SpidBlocked] [INT] NULL,
[WaitType] [VARCHAR] (255) NULL,
[WaitTime] [BIGINT] NULL,
[PhysicalIO] [BIGINT] NULL,
[CPUInSeconds] [BIGINT] NULL,
[MemoryUsed] [BIGINT] NULL,
[Name] [NVARCHAR] (128) NOT NULL,
[NumberOfOpenTransactions] [TINYINT] NULL,
[Status] [VARCHAR] (30) NULL,
[HostName] [VARCHAR] (50) NULL,
[ProgramName] [VARCHAR] (100) NULL,
[CommandIssued] [VARCHAR] (100) NULL,
[DomainName] [VARCHAR] (100) NULL,
[DomainUserName] [VARCHAR] (200) NULL,
[LoginName] [VARCHAR] (100) NULL,
[EventTpe] [VARCHAR] (255) NULL,
[Parameters] [VARCHAR] (255) NULL,
[EventInfo] [VARCHAR] (4000) NULL,
[CommandText] [VARCHAR] (MAX) NULL
)
ON primary
Next comes the stored procedure. We have to get creative if we want to capture blocking chains under a minute. To do that we side step the sql agent a bit and have it start our job and let it run. The procedure then enters a loop and waits.
The procedure is pretty self explanatory and follows a pattern you will see me use again for gathering information at a resolution less than one minute. @Recivers should be a list of emails separated by a semicolon(;). the “ignore” variables are all comma separated lists. You may wish to ignore some things to keep the noise level down.
CREATE PROCEDURE Alertonblocking @Duration DATETIME = '08:00:00',
-- Duration of data collection in hours.
@IntervalSec INT = 30,
-- Approximate time in seconds the gathering interval.
@MaxWaitTime INT = 28000,
-- This is in milliseconds.
@Recivers VARCHAR(8000) =
'test@email.com',-- Who all gets the emails.
@ProcessesToIgnore VARCHAR(8000) = '',
-- Ignore any processes that you don't want to trigger an alert.
@HostsToIgnore VARCHAR(8000) = '',
-- Ignore any host that you don't want to trigger an alert.
@LoginsToIgnore VARCHAR(8000) = ''
-- Ignore any login that you don't want to trigger an alert.
AS
SET nocount ON
CREATE TABLE #active_spids
(
spid INT,
blocked INT,
waittype VARCHAR(255),
waittime BIGINT,
physical_io BIGINT,
cpu BIGINT,
memusage BIGINT,
[dbid] INT,
open_tran TINYINT,
[status] VARCHAR(30),
hostname VARCHAR(50),
[program_name] VARCHAR(100),
cmd VARCHAR(100),
nt_domain VARCHAR(100),
nt_username VARCHAR(200),
loginame VARCHAR(100),
[sql_handle] [BINARY] (20) NOT NULL,
[stmt_start] [INT] NOT NULL,
[stmt_end] [INT] NOT NULL,
[sql_text] [VARCHAR] (MAX)
)
CREATE TABLE #active_spids_info
(
spid INT,
blocked INT,
waittype VARCHAR(255),
waittime BIGINT,
physical_io BIGINT,
cpu BIGINT,
memusage BIGINT,
[dbid] INT,
open_tran TINYINT,
[status] VARCHAR(30),
hostname VARCHAR(50),
[program_name] VARCHAR(100),
cmd VARCHAR(100),
nt_domain VARCHAR(100),
nt_username VARCHAR(200),
loginame VARCHAR(100),
[sql_handle] [BINARY] (20) NOT NULL,
[stmt_start] [INT] NOT NULL,
[stmt_end] [INT] NOT NULL,
eventtype VARCHAR(255),
parameters VARCHAR(255),
eventinfo VARCHAR(4000),
[text] [VARCHAR] (MAX)
)
CREATE TABLE #event_info
(
spid INT,
eventtype VARCHAR(255),
[Parameters] VARCHAR(255),
eventinfo VARCHAR(4000)
)
DECLARE @TerminateGatheringDT DATETIME,-- when to stop gathering
@WaitFor_Interval DATETIME,
@LastRecordingDT DATETIME,
@RecordingDT DATETIME,
@myError INT,-- Local copy of @@ERROR
@myRowCount INT,-- Local copy of @@RowCount
@msgText NVARCHAR(4000),-- for error messages
@dbname VARCHAR(255),
@svrname VARCHAR(255),
@datestart AS DATETIME,
@tstamp VARCHAR(255),
@spid1 VARCHAR(255),
@dbname1 VARCHAR(255),
@status VARCHAR(255),
@hostname VARCHAR(255),
@programname VARCHAR(255),
@cmd VARCHAR(255),
@nt_domain VARCHAR(255),
@nt_username VARCHAR(255),
@loginame VARCHAR(255),
@text VARCHAR(8000),
@msg VARCHAR(8000),
@sub VARCHAR(8000),
@timestamp AS DATETIME,
@spid INT,
@sqlhandle BINARY(20),
@tsqlhandle AS VARCHAR(255),
@waittime VARCHAR(255),
@waittype VARCHAR(255),
@buffer VARCHAR(255),
@diffmsec BIGINT
--SET @Duration = '08:00:00' -- Duration of data collection
--SET @IntervalSec = 30 -- Approx sec in the gathering interval
--SET @MaxWaitTime = 28000 -- This is in miliseconds!!!
--SET @Recivers = '' --who all gets the emails
SET @diffmsec = Datediff(ms, CONVERT(DATETIME, '00:00:00', 8), @Duration)
SELECT @WaitFor_Interval = Dateadd (s, @IntervalSec,
CONVERT (DATETIME, '00:00:00', 108
)),
@TerminateGatheringDT = Dateadd(ms, @diffmsec, Getdate())
WHILE Getdate() <= @TerminateGatheringDT
BEGIN
TRUNCATE TABLE #active_spids
TRUNCATE TABLE #active_spids_info
TRUNCATE TABLE #event_info
INSERT INTO #active_spids
SELECT spid,
blocked,
waittype,
waittime,
physical_io,
cpu,
[memusage],
a.dbid,
open_tran,
a.status,
hostname,
[program_name],
cmd,
nt_domain,
nt_username,
loginame,
[sql_handle],
[stmt_start],
[stmt_end],
[text]
FROM (SELECT spid,
blocked,
'waittype' = CASE
WHEN waittype = 0x0001 THEN
'Exclusive table lock'
WHEN waittype = 0x0003 THEN
'Exclusive intent lock'
WHEN waittype = 0x0004 THEN
'Shared table lock'
WHEN waittype = 0x0005 THEN
'Exclusive page lock'
WHEN waittype = 0x0006 THEN
'Shared page lock'
WHEN waittype = 0x0007 THEN
'Update page lock'
WHEN waittype = 0x0013 THEN
'Buffer resource lock (exclusive) request'
WHEN waittype = 0x0013 THEN
'Miscellaneous I/O (sort, audit, direct xact log I/O)'
WHEN waittype = 0x0020 THEN 'Buffer in I/O'
WHEN waittype = 0x0022 THEN 'Buffer being dirtied'
WHEN waittype = 0x0023 THEN 'Buffer being dumped'
WHEN waittype = 0x0081 THEN 'Write the TLog'
WHEN waittype = 0x0200 THEN 'Parallel query coordination'
WHEN waittype = 0x0208 THEN 'Parallel query coordination'
WHEN waittype = 0x0420 THEN 'Buffer I/O latch'
WHEN waittype = 0x0421 THEN 'Buffer I/O latch'
WHEN waittype = 0x0422 THEN 'Buffer I/O latch'
WHEN waittype = 0x0423 THEN 'Buffer I/O latch'
WHEN waittype = 0x0424 THEN 'Buffer I/O latch'
WHEN waittype = 0x0425 THEN 'Buffer I/O latch'
WHEN waittype = 0x0800 THEN 'Network I/O completion'
WHEN waittype = 0x8001 THEN 'Exclusive table lock'
WHEN waittype = 0x8003 THEN 'Exclusive intent lock'
WHEN waittype = 0x8004 THEN 'Shared table lock'
WHEN waittype = 0x8005 THEN 'Exclusive page lock'
WHEN waittype = 0x8006 THEN 'Shared page lock'
WHEN waittype = 0x8007 THEN 'Update page lock'
WHEN waittype = 0x8011 THEN
'Buffer resource lock (shared) request'
ELSE 'OLEDB/Miscellaneous'
END,
waittime,
physical_io,
cpu,
[memusage],
sp.dbid,
open_tran,
status,
hostname,
[program_name],
cmd,
nt_domain,
nt_username,
loginame,
[sql_handle],
[stmt_start],
[stmt_end],
[text]
FROM MASTER.dbo.sysprocesses sp WITH(nolock)
CROSS APPLY sys.Dm_exec_sql_text([sql_handle]))a
WHERE blocked > 0
AND waittime > @MaxWaitTime
UNION ALL
SELECT spid,
blocked,
waittype,
waittime,
physical_io,
cpu,
[memusage],
a.dbid,
open_tran,
a.status,
hostname,
[program_name],
cmd,
nt_domain,
nt_username,
loginame,
[sql_handle],
[stmt_start],
[stmt_end],
[text]
FROM (SELECT spid,
blocked,
'waittype' = CASE
WHEN waittype = 0x0001 THEN
'Exclusive table lock'
WHEN waittype = 0x0003 THEN
'Exclusive intent lock'
WHEN waittype = 0x0004 THEN
'Shared table lock'
WHEN waittype = 0x0005 THEN
'Exclusive page lock'
WHEN waittype = 0x0006 THEN
'Shared page lock'
WHEN waittype = 0x0007 THEN
'Update page lock'
WHEN waittype = 0x0013 THEN
'Buffer resource lock (exclusive) request'
WHEN waittype = 0x0013 THEN
'Miscellaneous I/O (sort, audit, direct xact log I/O)'
WHEN waittype = 0x0020 THEN 'Buffer in I/O'
WHEN waittype = 0x0022 THEN 'Buffer being dirtied'
WHEN waittype = 0x0023 THEN 'Buffer being dumped'
WHEN waittype = 0x0081 THEN 'Write the TLog'
WHEN waittype = 0x0200 THEN 'Parallel query coordination'
WHEN waittype = 0x0208 THEN 'Parallel query coordination'
WHEN waittype = 0x0420 THEN 'Buffer I/O latch'
WHEN waittype = 0x0421 THEN 'Buffer I/O latch'
WHEN waittype = 0x0422 THEN 'Buffer I/O latch'
WHEN waittype = 0x0423 THEN 'Buffer I/O latch'
WHEN waittype = 0x0424 THEN 'Buffer I/O latch'
WHEN waittype = 0x0425 THEN 'Buffer I/O latch'
WHEN waittype = 0x0800 THEN 'Network I/O completion'
WHEN waittype = 0x8001 THEN 'Exclusive table lock'
WHEN waittype = 0x8003 THEN 'Exclusive intent lock'
WHEN waittype = 0x8004 THEN 'Shared table lock'
WHEN waittype = 0x8005 THEN 'Exclusive page lock'
WHEN waittype = 0x8006 THEN 'Shared page lock'
WHEN waittype = 0x8007 THEN 'Update page lock'
WHEN waittype = 0x8011 THEN
'Buffer resource lock (shared) request'
ELSE 'OLEDB/Miscellaneous'
END,
waittime,
physical_io,
cpu,
[memusage],
sp.dbid,
open_tran,
status,
hostname,
[program_name],
cmd,
nt_domain,
nt_username,
loginame,
[sql_handle],
[stmt_start],
[stmt_end],
[text]
FROM MASTER.dbo.sysprocesses sp WITH(nolock)
CROSS APPLY sys.Dm_exec_sql_text([sql_handle])
WHERE spid IN (SELECT blocked
FROM MASTER.dbo.sysprocesses WITH(nolock)
WHERE blocked > 0
AND waittime > @MaxWaitTime)) a
ORDER BY blocked
--loop through the spids without a cursor
WHILE (SELECT COUNT(spid)
FROM #active_spids) > 0
BEGIN
SET @spid = (SELECT TOP 1 spid
FROM #active_spids
ORDER BY spid)
--grab the top spid
INSERT INTO #active_spids_info
(spid,
blocked,
waittype,
waittime,
physical_io,
cpu,
[memusage],
dbid,
open_tran,
status,
hostname,
[program_name],
cmd,
nt_domain,
nt_username,
loginame,
[sql_handle],
[stmt_start],
[stmt_end],
[text])
SELECT TOP 1 spid,
blocked,
waittype,
waittime,
physical_io,
cpu,
[memusage],
dbid,
open_tran,
status,
hostname,
[program_name],
cmd,
nt_domain,
nt_username,
loginame,
[sql_handle],
[stmt_start],
[stmt_end],
[sql_text]
FROM #active_spids
ORDER BY spid
INSERT INTO #event_info
(eventtype,
parameters,
eventinfo)
EXEC('DBCC INPUTBUFFER (' + @spid + ') WITH NO_INFOMSGS')
--get the inputbuffer
EXEC('update #event_info set spid = '+@spid+' where spid IS NULL')
--add the spid to the input buffer data
SELECT @sqlhandle = sql_handle
FROM #active_spids
WHERE spid = @spid
DELETE FROM #active_spids
WHERE spid = @spid
--remove the spid processed
END
UPDATE #active_spids_info
SET #active_spids_info.eventtype = #event_info.eventtype,
#active_spids_info.parameters = #event_info.parameters,
#active_spids_info.eventinfo = #event_info.eventinfo
FROM #active_spids_info,
#event_info
WHERE #active_spids_info.spid = #event_info.spid
--join all the info into one table
SET @timestamp = Getdate()
--select statement to return results
INSERT INTO management.dbo.blockingchains
SELECT @@SERVERNAME,
@timestamp AS tstamp,
a.spid,
a.blocked,
a.waittype,
a.waittime,
a.physical_io,
( a.cpu / 1000 ) AS cpu_in_seconds,
a.[memusage],
b.[name],
a.open_tran,
a.status,
a.hostname,
a.[program_name],
a.cmd,
a.nt_domain,
a.nt_username,
a.loginame,
a.eventtype,
a.parameters,
a.eventinfo,
a.TEXT
FROM #active_spids_info a
INNER JOIN MASTER.dbo.sysdatabases b
ON a.dbid = b.dbid
IF ( (SELECT MAX(sampletime)
FROM management.dbo.blockingchains
WHERE spidblocked = 0
AND programname NOT IN( @ProcessesToIgnore )
AND hostname NOT IN( @HostsToIgnore )
AND ( domainname NOT IN( @LoginsToIgnore )
OR loginname NOT IN( @LoginsToIgnore ) )) =
@timestamp
)
BEGIN
SELECT @sub = 'Blocking Issues - ' + @@SERVERNAME
SELECT @tstamp = sampletime,
@spid1 = spid,
@status = status,
@hostname = Isnull(hostname, ''),
@programname = Isnull([programname], ''),
@cmd = Isnull(commandissued, ''),
@nt_domain = Isnull(domainname, ''),
@nt_username = Isnull(domainusername, ''),
@loginame = Isnull(loginname, ''),
@text = Isnull(commandtext, ''),
@waittime = (SELECT MAX(waittime)
FROM management.dbo.blockingchains
WHERE sampletime = (SELECT MAX(sampletime)
FROM
management.dbo.blockingchains)),
@waittype = Isnull(waittype, ''),
@buffer = Isnull(eventinfo, '')
FROM management.dbo.blockingchains
WHERE sampletime = (SELECT MAX(sampletime)
FROM management.dbo.blockingchains)
AND spidblocked = 0
SELECT @msg =
'The user below is at the head of the blocking chain on the listed server:'
+
CHAR(13) +
'__________________________________________________________________________'
+
CHAR(13) + 'Server Name:' + @@SERVERNAME + CHAR(13) +
'TimeStamp: ' + @tstamp + CHAR(13) + 'SPID: ' + @spid1 + CHAR(
13)
+ 'Login Name: ' + @loginame + CHAR(13) + 'NT Domain: ' + @nt_domain + CHAR(
13)
+ 'NT Username: ' + @nt_username + CHAR(13) + 'Host Name: ' + @hostname +
CHAR(
13) + 'Command: ' + @cmd + CHAR(13) + 'Program Name: ' +
@programname + CHAR(13) + 'Wait Type: ' + @waittype + CHAR(13)
+
'Maximum Wait Time For Blocked Thread: ' + @waittime + CHAR(13
) +
'Input Buffer: ' + @buffer + CHAR(13) + 'Status: ' + @status +
CHAR(13) + 'SQL String:' + CHAR(13) +
'--WARNING CAN BE LONG AND MAY NOT BE THE WHOLE TEXT!!!--' +
CHAR(
13) + @text
EXEC msdb.dbo.Sp_send_dbmail
@recipients = @Recivers,
@body = @msg,
@subject = @sub;
END
WAITFOR delay @WaitFor_Interval -- delay
END
DROP TABLE #active_spids
DROP TABLE #active_spids_info
DROP TABLE #event_info
If you find a bug or have an issue just add a comment here and I’ll address it.
UPDATE 5/30/2011
status was a varchar(20) should have been a varchar(30)
