PRB: Memory Leaks in SQL Srv Driver During Connect/Disconnect

 Last reviewed: September 9, 1996
Article ID: Q132494
The information in this article applies to:
  • Microsoft Open Database Connectivity, versions 2.0 and 2.5

SYMPTOMS

The following sequence of calls: 

   SQLAllocEnv, SQLAllocConnect, SQLConnect (or SQLDriverConnect),
   SQLDisconnect, SQLFreeConnect, and SQLFreeEnv
can lead to a 4K memory leak in the following Microsoft SQL Server drivers:
  • 16-bit SQL Server Driver 2.00.1912, ships with SQL Server version 4.21a
  • 32-bit SQL Server Driver 2.00.1912, ships with SQL Server version 4.21a
  • 16-bit SQL Server Driver 2.50.0121, ships with SQL Server version 6.0

CAUSE

STEPS TO CHECK 32-BIT SQL SERVER DRIVER MEMORY LEAKS:

Start the Process Viewer in the NT Resource Kit. Start the 32-bit ODBC Test application.

  1. Inside P-Viewer, select ODBCTE32, click Refresh, and write down the number of "Heap Usage."

  2. Inside 32-bit ODBC Test:

    a. From the Connect menu, select SQLAllocEnv.

    b. From the Connect menu, select SQLAllocConnect.

    c. From the Connect menu, select SQLConnect and connect to SQL Server 

          data source. Alternatively, you can select SQLDriverConnect instead
      of SQLConnect.

    d. From the Connect menu, select SQLDisconnect, SQLFreeConnect, and 

          SQLFreeEnv.

  3. Go back to P-Viewer, click Refresh, again write down the number of "Heap Usage."

Process Viewer will show 4K memory leaks in the SQL Server Drivers mentioned above. Every time you repeat steps 2.a through 2.d, another 4K of memory stays allocated.

NOTE: There is no memory leakage in the 32-bit SQL Server driver 2.50.0121 that ships with SQL Server version 6.0.

WORKAROUND

Share ODBC connections as much as possible in the application.

Additional reference words: 2.00.1912 2.50.0121 sql6 6.00 4.21a
KBCategory: kbprb kbprg
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Last reviewed: September 9, 1996
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