CODEWITHSUNDEEP
delphi
Artso
Artso

Reputation: 19

Delphi out of memory error when dowload file

I'm trying to download a file of 500 mb more when it's in this size gives out of memory error. I tried switching to 64 bit application and it worked. But I would need it to work in 32 bit application to download file.

var
  Stream: TStream;
  fileStream: TFileStream;
  Buffer: PByte;
  BytesRead, BufSize: Integer;
  Size: int64;
begin
  BufSize := 1024;
  fileStream:= TFileStream.Create(GetCurrentDir()+'\DownloadFile.zip', 
                                  fmCreate);
  GetMem(Buffer, BufSize);

  Stream := getDownload(size);

  if (Size <> 0) then
  begin
    repeat
       BytesRead := Stream.Read(Pointer(Buffer)^, BufSize);

       if (BytesRead > 0) then
       begin
          fileStream.WriteBuffer(Pointer(Buffer)^, BytesRead);
       end;
       Application.ProcessMessages
    until (BytesRead < BufSize);

    if (Size <> fileStream.Size) then
    begin
      exit;
    end;
  end;

  finally
     FreeMem(Buffer, BufSize);
     fileStream.Destroy;
  end;
end;   

function TServiceMethods.getDownload(out Size: Int64): TStream;
begin
  Result := TFileStream.Create(GetCurrentDir+'\DownloadFile.zip', fmOpenRead 
  or fmShareDenyNone);
  Size := Result.Size;
  Result.Position := 0;
end;

Upvotes: 0

Views: 607

Answers (1)

David Heffernan
David Heffernan

Reputation: 612884

Don't use a memory stream here. That forces the entire file into a contiguous block of memory, which as you discovered exhausts memory in a 32 bit process.

Instead, write the downloaded data directly to file. You can remove the intermediate memory stream and write directly to a file stream.

Of course, all of this assumes that getDownload returns a stream that performs the download as you read it. If getDownload reads the entire file into a memory stream then it suffers from the exact same problem as the code in this question.

Upvotes: 5

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