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HTTP File Upload Operation Takes a Long Time to Complete

Article ID: 329781 - View products that this article applies to.

This article was previously published under Q329781

SYMPTOMS

When you use the HTTP File Upload feature to upload multi-megabyte files, the upload operation may take a very long time to complete.

Note This issue is documented in Request For Comment (RFC) 1867, "Form-based File Upload in HTML."

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CAUSE

This issue occurs because the default Winsock Send buffer is 8 kilobytes (KB), and therefore Internet Explorer supplies the data in 8 KB chunks. On an average network, this equals approximately 80 KB per second (KBps), regardless of network bandwidth.

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

214397

(http://support.microsoft.com/kb/214397/EN-US/ )

INFO: Design Issues - Sending Small Data Segments Over TCP w/Winsock

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RESOLUTION

To resolve this issue, configure Internet Explorer to increase the Send buffer when communicating with Winsock. This increases network performance when you use the HTTP File Upload method. To do this, follow these steps.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756

(http://support.microsoft.com/kb/322756/ )

How to back up and restore the registry in Windows

Start Registry Editor (Regedt32.exe).
Locate and then click the following registry key:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
On the Edit menu, click Add Value, and then add the following registry value:
Value name: SocketSendBufferLength
Data type: REG_DWORD
Radix: Decimal
Value data: Buffer size that you want (in bytes)
Buffer size value options:
16-KB Buffer = 16384
24-KB Buffer = 24576
32-KB Buffer = 32768
40-KB Buffer = 40960
48-KB Buffer = 49152
56-KB Buffer = 57344
64-KB Buffer = 65536
Collapse this tableExpand this table
Note Buffers sizes larger than those specified here are not supported by Microsoft.
Quit Registry Editor.

Make sure that you test each value, starting with a 16-KB buffer. When the upload performance becomes acceptable, select the corresponding buffer value.

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STATUS

This behavior is by design.

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MORE INFORMATION

When you use the procedure described in the "Resolution" section of this article, any program that uses the WININETAPI HTTPSendRequest function (as documented on the following Microsoft Developer Network (MSDN) Web site) will allocate and request a Winsock Send buffer, as defined by the registry key.

For additional information about the HTTPSendRequest function, visit the following MSDN Web site:

http://msdn2.microsoft.com/en-us/library/aa384247.aspx

(http://msdn2.microsoft.com/en-us/library/aa384247.aspx)

For additional information about Winsock Send Buffer behavior, click the article number below to view the article in the Microsoft Knowledge Base:

214397

(http://support.microsoft.com/kb/214397/EN-US/ )

INFO: Design Issues - Sending Data Segments Over TCP w/Winsock

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