URLDownloadToFile API Leaking Memory

[Fencliff]

Hi,

I have a problem with the URLDownloadToFile API reserving a large chunk of memory, and I can't figure out how to free it. My program is an app that runs in the background, downloading multiple Excel workbooks (.xls) from a web page.

When the first file is downloaded, the memory usage of the process jumps from ~5Mb to ~70Mb and stays there. The memory consumption doesn't increase with subsequent calls to the API.

Here is the relevant code:

Private Declare Function URLDownloadToFile Lib "urlmon" Alias _
        "URLDownloadToFileA" ( _
        ByVal pCaller As Long, _
        ByVal szURL As String, _
        ByVal szFileName As String, _
        ByVal dwReserved As Long, _
        ByVal lpfnCB As Long) As Long


Private Const ERROR_SUCCESS As Long = 0
Private Const BINDF_GETNEWESTVERSION As Long = &H10
Private Const INTERNET_FLAG_RELOAD As Long = &H80000000

Public Function bHTTPDownloadFile(sSourceUrl As String, _
                sLocalFile As String) As Boolean
  
  'Download the file. BINDF_GETNEWESTVERSION forces the API to download from the specified source.
  'Passing 0& as dwReserved causes the locally-cached copy to be downloaded, if available. If the API
  'returns ERROR_SUCCESS (0), DownloadFile returns True.
   bHTTPDownloadFile = URLDownloadToFile(0&, _
                                    sSourceUrl, _
                                    sLocalFile, _
                                    BINDF_GETNEWESTVERSION, _
                                    0&) = ERROR_SUCCESS
                                    
End Function

Worthy of noticing, that the exact same behavior is elicited when calling the API with null arguments, as instructed on some websites:

URLDownloadToFile(0, sSourceUrl, sLocalFile, 0, 0)

Does anybody have any idea why this is happening? Any tidbit of information would be valuable.

 

[Fencliff]

Please note I have posted same question at VB Forums at

http://www.vbforums.com/showthread.php?p=3202011