FIX: Handle Leak Occurs in SQL Server When Service or Application Repeatedly Connects and Disconnects with Shared Memory Network Library

• Reuse open connections as much as possible instead of opening and closing them frequently.
• Use a network library other than the shared memory network library.

Back to the top

Steps to Reproduce the Behavior

1. Copy the following code into a Microsoft Visual C++ console application, and then compile the application:

   #include "stdafx.h"
   
   #import "C:\Program Files\Common Files\System\ado\msado21.tlb" rename("EOF", "adoEOF")
   #include <crtdbg.h>
   
   bool bRunFree = true;
   
   BOOL WINAPI ConsoleCtrlHandler(DWORD dwCtrlType)
   {
       switch (dwCtrlType)
       {
       case CTRL_C_EVENT:
       case CTRL_BREAK_EVENT:
       case CTRL_CLOSE_EVENT:
       case CTRL_LOGOFF_EVENT:
       case CTRL_SHUTDOWN_EVENT:
   		bRunFree = false;
           break;
       default:
           break;
       }
   
       return TRUE;
   }
   
   int main(int argc, char* argv[])
   {
   	_bstr_t sConnectionString = L"Provider=SQLOLEDB;database=Northwind;integrated security=SSPI;server=(local);";
   	HANDLE hOutput = GetStdHandle(STD_OUTPUT_HANDLE);
   	COORD coord = { 0, 1 };
   	_bstr_t sEmpty;
   	int nCount = 0;
   
   	printf("Starting, Press CTRL+C to end\n");
   
       if (SetConsoleCtrlHandler(ConsoleCtrlHandler, TRUE) == FALSE)
   	{
   		printf("SetConsoleCtrlHandler failed 0x%08X", GetLastError());
   	}
   
   	CoInitialize(NULL);
   
   	while (bRunFree)
   	{
   		ADODB::_ConnectionPtr piConnection;
   		HRESULT hRes = piConnection.CreateInstance(__uuidof(ADODB::Connection));
   
   		if (FAILED(hRes))
   		{
   			printf("CreateInstance failed 0x%08X", hRes);
   		}
   		else
   		{
   			_ASSERTE(piConnection->GetState() == ADODB::adStateClosed);
   			hRes = piConnection->Open(sConnectionString, sEmpty, sEmpty, -1);
   
   			if (FAILED(hRes))
   			{
   				printf("Open failed 0x%08X", hRes);
   				break;
   			}
   
   			_ASSERTE(piConnection->GetState() == ADODB::adStateOpen);
   			piConnection->Close();
   			SetConsoleCursorPosition(hOutput, coord);
   			printf("Connection Opened/Closed %d times\n", ++nCount);
   
   			piConnection = NULL;
   		}
   	}
   
   	CoUninitialize();
   
   	return 0;
   }
   						

2. Open Task Manager, and then click the Processes tab.
3. On the View menu, click Select Columns, and then click to select the Handles Count check box to add handles to the columns that are monitored.
   
   Alternatively, you can use Performance Monitor to record the handle count for the SQL Server process.
4. Run the code for several minutes. Notice that the count of handles increases steadily.

Back to the top