PRB: PUBLIC Variables Not Released from InProcess Servers in ASP

ID: Q247319

The information in this article applies to:

Microsoft Visual FoxPro for Windows, version 6.0

SYMPTOMS

Public variables declared in an in-process Microsoft Visual FoxPro OLE Automation Server, launched from an ASP page, are not released when the OLE Automation Server is released.

CAUSE

PUBLIC variables declared within an in-process OLE Automation Server are public to the thread and any object on the thread. PUBLIC variables are not released until the thread has been uninitialized and the client has unloaded the in-process server. Setting the instance of the in-process server object to "nothing" does not unload the server.

RESOLUTION

Set the scope of variables used within in-process OLE Automation Servers, used with Active Server Pages, to PRIVATE rather than PUBLIC.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

Create a new project named MTHREAD.

Add a new program file to the project, using the following code:


DEFINE CLASS mthread AS CUSTOM OLEPUBLIC

   FUNCTION PublicHit
      LPARAMETER lnSecs
      LOCAL x
      lnSecs=IIF(EMPTY(lnSecs),0,lnSecs)

      IF lnSecs > 60
         lnSecs = 61
      ENDIF

      IF VARTYPE(gnPubValue) = "N"
         gnPubValue = gnPubValue + 1
      ELSE
         PUBLIC gnPubValue
         gnPubValue = 1
      ENDIF

      IF VARTYPE(gnPrivValue) = "N"
         gnPrivValue = gnPrivValue + 1
      ELSE
         PRIVATE gnPrivValue
         gnPrivValue = 1
      ENDIF

      DECLARE Sleep IN WIN32API INTEGER
      FOR x=1 TO lnSecs
         FOR x=1 TO lnSecs
            Sleep(1000)
         ENDFOR
      ENDFOR

      DECLARE INTEGER GetCurrentThreadId IN WIN32API
      lcHTML = [<p><table style="background:black;color:white">] + CHR(13) + ;
         [<tr><td style="font:normal normal 14pt Verdana">] + ;
         "The request completed in " + TRANS(lnSecs) + " seconds." + [</td></tr>] +CHR(13) +;
         [<table>] + CHR(13) + ;
         "The current Thread ID is: " + TRANS(GetCurrentThreadId()) + "<p>"+CHR(13) + ;
         "The Public Value  (gnPubValue) : = " + TRANS(gnPubValue) + "<br>"+ CHR(13) + ;
         "The Private Value (gnPrivValue): = " + TRANS(gnPrivValue) + "<br>"

      RETURN lcHTML
   ENDFUNC
ENDDEFINE

Click the Build button on the Project Manager, and select either a Single-threaded COM server (dll) or a Multi-threaded COM server (dll).

Install the COM Server and run-time files on a computer running Internet Information Server.

Create an Active Server Page named TEST.ASP in the IIS WWWROOT directory using the following code, and make certain that the directory has execute privileges:


<%@ Language=VBScript %>
<HTML>
<HEAD>
<META NAME="GENERATOR" Content="Microsoft Visual Studio 6.0">
</HEAD>
<BODY>

<%
Set oVFPApp = Server.CreateObject("mthread.mthread")

Response.Write oVFPApp.PublicHit

set oVFPApp = nothing

%>	

</BODY>
</HTML>

Launch your Web Browser and navigate to the Active Server Page that was created in step 4. Refresh the page several times, and note that the value of gnPubValue is incremented each time the page is refreshed.

Close your Web Browser.

Launch your Web Browser and navigate to the Active Server Page that was created in step 4. Note that the value of gnPubValue is not 1.

REFERENCES

Q156547 HOWTO: Manually Register a Custom OLE Server

Q156014 HOWTO: Set Up OLE Automation in Visual FoxPro

Additional query words:

Keywords : kbAutomation kbInternet kbVFp600 kbGrpFox kbDSupport
Version : WINDOWS:6.0
Platform : WINDOWS
Issue type : kbprb