DOCUMENT:Q168250  12-MAY-2001  [odbc]
TITLE   :FIX: IIS Performance Degrades with a Bad Connection
PRODUCT :Open Database Connectivity (ODBC)
PROD/VER:WINDOWS:3.0; winnt:3.0
OPER/SYS:
KEYWORDS:kbinterop kbprogramming

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The information in this article applies to:

 - Microsoft Open Database Connectivity, version 3.0 
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BUG #: 4636 (odbc3)

SYMPTOMS
========

Microsoft Internet Information Server (IIS) version 3.0 may experience degrading
performance when there is a bad connection in the ODBC connection pool and the
backend database server for the bad connection is not available for connecting.

CAUSE
=====

With connection pooling enabled, whenever IIS users try to connect to the same
backend database server, the ODBC driver manager tests the existing connection
in the pool before reusing the connection. If there is a bad connection in the
pool and the backend database server for the bad connection is unavailable, the
ODBC driver manager keeps testing the bad connection, and IIS essentially
creates a thread for each attempted connection. The testing connection process
takes time, and the IIS threads are also being generated continuously, which
causes the performance to degrade.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Open Database
Connectivity version 3.0. This problem has been corrected in U.S. Service Pack 1
for Microsoft Open Database Connectivity, version 3.0. For more information,
contact your primary support provider.


MORE INFORMATION
================

A new registry key and ODBC API have been introduced to avoid testing the
connection continuously. The new registry key is under:

   HKEY_LOCAL_MACHINE\Software\Odbc\ODBCINST.INI \ODBC Connection Pooling\Retry
   Wait

The Retry Wait registry key is a value of REG_SZ and the default value is 120 (in
second). The value for the Retry Wait registry key can be set by calling
ODBCSetTryWaitValue ODBC API. The ODBCSetTryWaitValue API takes a DWORD
argument.

If there is a bad connection in the pool, the ODBC driver manager will attempt to
connect before the connection can be reused for the first time. If the
connection still fails, the ODBC driver manager returns the error and marks the
connection with the time. From that point until the RetryWait value expires, the
ODBC driver manager returns a failure without testing the connection.

Additional query words: timeout asp

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Keywords          : kbinterop kbprogramming 
Technology        : kbAudDeveloper kbODBCSearch kbODBC300
Version           : WINDOWS:3.0; winnt:3.0
Issue type        : kbbug
Solution Type     : kbfix

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