The W3wp.exe process uses almost 100 percent of CPU resources when you synchronize large email messages in Exchange Server 2003 Service Pack 2

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Article ID: 941439 - View products that this article applies to.
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Symptoms

You use Microsoft Exchange ActiveSync to synchronize with a mailbox on a server that is running Microsoft Exchange Server 2003 Service Pack 2 (SP2). If Exchange Server 2003 SP2 contains email messages that are larger than 10 MB, the Exchange ActiveSync W3wp.exe process uses almost 100 percent of CPU resources for a long time on Exchange Server 2003 SP2.

Cause

This problem occurs because Exchange Server 2003 SP2 must allocate memory to process the message in 4-KB increments. Therefore, it can take thousands of allocations to handle a large message. This behavior consumes lots of CPU resources.

Resolution

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 this specific problem. 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:
http://support.microsoft.com/contactus/?ws=support
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 Exchange Server 2003 SP2 installed.

Restart requirement

You do not have to restart the computer after you apply this hotfix. However, the IIS Admin Service and all dependent services are restarted when you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released 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.
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File nameFile versionFile sizeDateTime
Massync.dll6.5.7653.19757,76001-Nov-200717:03


After you apply this hotfix, you can set the MaxAllocationIncrement registry value to control how memory is allocated when an Exchange ActiveSync device is synchronized.

Note For more information about how to set an appropriate MaxAllocationIncrement value, see the "More Information" section.

Note The MaxAllocationIncrement registry value is located under the following registry subkey:
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Subkey:Value:Type:Data:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MasSync\Parameters
MaxAllocationIncrementREG_DWORDStart with a 4-KB increment and double with every increment until the maximum allowed increment value is reached.
For example, the data can be 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, and so on.

Status

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

More information

After you apply this hotfix, you can change the MaxAllocationIncrement value to more efficiently reallocate the memory that is used during Exchange ActiveSync device synchronization. By changing the MaxAllocationIncrement value, you can reduce the number of CPU requests that are made during synchronization.

Note After you change the MaxAllocationIncrement value, you must monitor how much free system memory is available to make sure that the system does not run out of memory.

When an Exchange ActiveSync device tries to synchronize an email message, 4 kilobytes (KB) of memory are allocated to the process the first time. If the initial allocation of 4 KB is not enough to synchronize the message, the initial memory allocation is doubled to 8 KB. If 8 KB is not enough to synchronize the message, the memory allocation is doubled again to 16 KB. This process of incrementing memory allocation continues until the value in the MaxAllocationIncrement subkey is reached. After the value in the MaxAllocationIncrement subkey is reached, memory is incremented by the value in the MaxAllocationIncrement subkey.

For example, consider the following scenarios when an Exchange ActiveSync device requests an email message that is 128 KB:

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Message SizeMaxAllocationIncrement ValueReallocation ValuesNumber of Reallocations
128Not applicable4, 8, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56. 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 124, 12830
12884, 8, 16, 24, 32, 48, 56, 64, 72, 80, 88, 96, 104, 112, 120, 12815
128164, 8, 16, 32, 48, 64, 80, 96, 112, 1289
128324, 8, 16, 32, 64, 96, 1286
Additionally, consider the following scenarios when an Exchange ActiveSync device requests an email message that is 20 megabytes (MB):

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Message SizeMaxAllocationIncrement ValueNumber of Reallocations
24,57651245
24,5768,19213

References

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates

For more information about the naming schema for Exchange Server software updates, click the following article number to view the article in the Microsoft Knowledge Base:
817903 New naming schema for Exchange Server software update packages


Properties

Article ID: 941439 - Last Review: September 3, 2013 - Revision: 4.0
Applies to
  • Microsoft Exchange Server 2003 Standard Edition
  • Microsoft Exchange Server 2003 Enterprise Edition
Keywords: 
kbautohotfix kbhotfixserver kbqfe KB941439

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