FIX: SQL Server 2008 R2 performs poorly when most threads wait for the CMEMTHREAD wait type if the threads use table variables or temp tables to load or update rowsets

Applies to: SQL Server 2008 R2 DeveloperSQL Server 2008 R2 EnterpriseSQL Server 2008 R2 Standard

Symptoms


Consider the following scenario:
  • You install an instance of Microsoft SQL Server 2008 R2 on a computer.
  • The threads in this instance constantly wait for the CMEMTHREAD wait type. Most of the threads use table variables or temp tables to load or update rowsets. For example, most of the threads run one of the following statements:
    • CREATE TABLE 
    • CREATE INDEX 
  • The contention for the LOCK_HASH spinlock is high. For example, the spin count, the possible collisions, and the back-off values for the LOCK_HASH spinlock increase very fast.

    Note For more information about how to monitor the LOCK_HASH spinlock, see the "More information" section.
In this scenario, SQL Server 2008 R2 might perform poorly.

Resolution


Cumulative update information

SQL Server 2008 R2

The fix for this issue was first released in Cumulative Update 6. For more information about how to obtain this cumulative update package for SQL Server 2008 R2, click the following article number to view the article in the Microsoft Knowledge Base:
2489376 Cumulative Update package 6 for SQL Server 2008 R2
Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2008 R2 fix release. We recommend that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
981356 The SQL Server 2008 R2 builds that were released after SQL Server 2008 R2 was released

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.


If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.


Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website:
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


Prerequisites

To apply this hotfix, you must have Microsoft SQL Server 2008 R2 installed.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfix.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

32-bit SQL Server 2008 R2 Database Services Core Instance
File nameFile versionFile sizeDateTimePlatform
atxcore.dll2009.100.1757.013,5520 8-Jan-110:37x86
datacollectorcontroller.dll2009.100.1757.0135,520 8-Jan-110:36x86
etwcls.mofNot applicable1,116,328 6-Jan-1121:54Not applicable
instmsdb.sqlNot applicable2,241,260 6-Jan-1120:23Not applicable
mssqlsystemresource.ldfNot applicable524,288 6-Jan-1123:51Not applicable
mssqlsystemresource.mdfNot applicable63,569,920 6-Jan-1123:51Not applicable
sql_engine_core_inst_keyfile.dll2009.100.1757.013,664 8-Jan-110:36x86
sqlaccess.dll2009.100.1757.0415,584 8-Jan-110:34x86
sqlagent.exe2009.100.1757.0367,968 8-Jan-110:37x86
sqlagent100_msdb_upgrade.sqlNot applicable2,371,245 6-Jan-1121:52Not applicable
sqlos.dll2009.100.1757.014,688 8-Jan-110:25x86
sqlscriptdowngrade.dll2009.100.1757.014,688 8-Jan-110:25x86
sqlscriptupgrade.dll2009.100.1757.04,611,424 8-Jan-110:25x86
sqlservr.exe2009.100.1757.042,899,808 8-Jan-110:37x86
sqsrvres.dll2009.100.1757.089,952 8-Jan-110:25x86

64-bit SQL Server 2008 R2 Database Services Core Instance
File nameFile versionFile sizeDateTimePlatform
atxcore.dll2009.100.1757.031,584 7-Jan-1123:36x64
datacollectorcontroller.dll2009.100.1757.026,2496 7-Jan-1123:36x64
etwcls.mofNot applicable1,116,328 6-Jan-1121:54Not applicable
instmsdb.sqlNot applicable2,241,260 6-Jan-1120:23Not applicable
mssqlsystemresource.ldfNot applicable524,288 6-Jan-1123:51Not applicable
mssqlsystemresource.mdfNot applicable63,569,920 6-Jan-1123:51Not applicable
sql_engine_core_inst_keyfile.dll2009.100.1757.014,176 7-Jan-1123:36x64
sqlaccess.dll2009.100.1757.0403,296 7-Jan-1123:35x86
sqlagent.exe2009.100.1757.0428,384 7-Jan-1123:37x64
sqlagent100_msdb_upgrade.sqlNot applicable2,371,245 6-Jan-1121:52Not applicable
sqlos.dll2009.100.1757.015,712 7-Jan-1123:35x64
sqlscriptdowngrade.dll2009.100.1757.015,712 7-Jan-1123:35x64
sqlscriptupgrade.dll2009.100.1757.04,610,912 7-Jan-1123:35x64
sqlservr.exe2009.100.1757.062,007,648 7-Jan-1123:37x64
sqsrvres.dll2009.100.1757.0105,824 7-Jan-1123:35x64
Itanium-architecture SQL Server 2008 R2 Database Services Core Instance
File nameFile versionFile sizeDateTimePlatform
atxcore.dll2009.100.1757.063,328 7-Jan-1123:01IA-64
datacollectorcontroller.dll2009.100.1757.0477,024 7-Jan-1123:01IA-64
etwcls.mofNot applicable1,116,328 6-Jan-1121:54Not applicable
instmsdb.sqlNot applicable2,241,260 6-Jan-1120:23Not applicable
mssqlsystemresource.ldfNot applicable524,288 6-Jan-1123:51Not applicable
mssqlsystemresource.mdfNot applicable63,569,920 6-Jan-1123:51Not applicable
sql_engine_core_inst_keyfile.dll2009.100.1757.019,296 7-Jan-1123:01IA-64
sqlaccess.dll2009.100.1757.0392,032 7-Jan-1122:59x86
sqlagent.exe2009.100.1757.01,205,600 7-Jan-1123:04IA-64
sqlagent100_msdb_upgrade.sqlNot applicable2,371,245 6-Jan-1121:52Not applicable
sqlos.dll2009.100.1757.022,368 7-Jan-1122:51IA-64
sqlscriptdowngrade.dll2009.100.1757.020,832 7-Jan-1122:51IA-64
sqlscriptupgrade.dll2009.100.1757.04,617,056 7-Jan-1122:51IA-64
sqlservr.exe2009.100.1757.0121,714,528 7-Jan-1123:04IA-64
sqsrvres.dll2009.100.1757.0188,768 7-Jan-1122:51IA-64

Status


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information


To monitor the LOCK_HASH spinlock, adjust the delay and number of iterations as appropriate for your environment in the following code, and then run that code:
SET NOCOUNT ON
CREATE TABLE #spins([Spinlock Name] varchar(50),Collisions numeric,Spins numeric,[Spins/Collision] float,[Sleep Time (ms)] numeric,Backoffs numeric, InsertTime datetime DEFAULT GETDATE())
DECLARE @counter int = 1
WHILE @counter < 10
BEGIN
INSERT INTO #spins ([Spinlock Name], Collisions, Spins, [Spins/Collision], [Sleep Time (ms)], Backoffs) EXECUTE ('DBCC SQLPERF (''SPINLOCKSTATS'') WITH NO_INFOMSGS')
WAITFOR DELAY '00:00:05'
SET @counter +=1
END
SELECT * FROM #spins WHERE [Spinlock Name] = 'LOCK_HASH' ORDER BY InsertTime
DROP TABLE #spins