Microsoft KB Archive/306365

= Microsoft Distributed Transaction Coordinator Does Not Flush Log Records Efficiently =

Article ID: 306365

Article Last Modified on 6/5/2003

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APPLIES TO

 Microsoft COM+ 1.0, when used with:  Microsoft Windows 2000 Service Pack 1

 Microsoft Windows 2000 Service Pack 2 

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This article was previously published under Q306365



SYMPTOMS
During a Transaction Processing Performance Council (TPC) benchmark test, Microsoft Distributed Transaction Coordinator (MS DTC) spends 50 percent of its time flushing log records to disk. MS DTC also spends approximately 10 percent of its time moving active connection objects from the active list to the free list.



CAUSE
The log manager has a single flush thread to flush log record pages to disk for all transactions. After the page is on the disk, the flush thread notifies all of the transactions whose records have been flushed. This single thread that notifies the transactions does not scale well on high-end enterprise scenarios.

While MS DTC holds a connection object and a spin lock, MS DTC searches the active list of connection objects in a linear fashion and moves this object to a free list.



RESOLUTION
To resolve this problem, obtain Microsoft COM+ hotfix rollup package 18.2. For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

317177 INFO: Availability of Windows 2000 Post-Service Pack 2 COM+ Hotfix Rollup Package 18.2

To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to Obtain the Latest Windows 2000 Service Pack

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STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows 2000 Service Pack 3.

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MORE INFORMATION
COM+ hotfix rollup package 18.2 improves MS DTC performance by four or five percent in a recent benchmark test. For more information, refer to the following Microsoft Web site:

Microsoft SQL Server Scales Up and Scales Out

http://www.microsoft.com/presspass/Press/2001/Sep01/09-20SQLBenchmarkPR.asp

For additional information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the article number below to view the article in the Microsoft Knowledge Base:

265173 The Datacenter Program and Windows 2000 Datacenter Server Product

For additional information about how to install multiple hotfixes with only one reboot, click the article number below to view the article in the Microsoft Knowledge Base:

296861 Use QChain.exe to Install Multiple Hotfixes with One Reboot

Additional query words: kbIISCom kbWin2000preSP3COMRollup182Fix TPC-C benchmarks performance improvement MSDTC communication manager

Keywords: kbbug kbfix kbwin2000presp3fix kbwin2000sp3fix kbdtc KB306365

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