call System.Runtime.InteropServices.Marshal.ReleaseComObject before setting object reference to null, also seehttp://dotnetjunkies.com/WebLog/wicwil/archive/2003/10/20/2733.aspx
When you call a COM+ or Microsoft Transaction Server (MTS) component from a .NET application, the object activates in the COM+ or MTS-hosted environment, but when the call completes, the object count does not decrease immediately. This is true even if the object is explicitly set to nothing (Visual Basic .NET) or null (C#) in the .NET client code. http://support.microsoft.com/default.aspx?scid=kb;en-us;305823
方法来释放COM+对象.但dllhost进程所用内存还是不停的增长.那位高人给一个例子.这个问题让我烦恼人好几天.