Clientdataset Speicherfreigabe

[himitsu]

Wenn du nur die Datensätze überschreibst, anstatt zu löschen und neu zu erstellen, dann gibt es kein Problem.
Aber man sollte dringend LogChanges abschalten, denn erstmal bremst das ja ganz extrem und es verbrät dennoch ordentlich Speicher.

Delphi-Quellcode:

{$OVERFLOWCHECKS OFF}

uses
  System.StrUtils, Data.DB, Datasnap.DBClient;

procedure TForm8.FormCreate(Sender: TObject);
var
  CDS: TClientDataSet;
  Mem: UInt64;
procedure ShowState;
  var
    GStatus: TMemoryStatusEx;
    MMState: TMemoryManagerState;
  begin
    GStatus.dwLength := SizeOf(GStatus);
    GlobalMemoryStatusEx(GStatus);

    GetMemoryManagerState(MMState);
    var FastMM: Int64 := 0;
    for var i := 0 to High(MMState.SmallBlockTypeStates) do
      Inc(FastMM, MMState.SmallBlockTypeStates[i].UseableBlockSize * MMState.SmallBlockTypeStates[i].AllocatedBlockCount);
    Inc(FastMM, MMState.TotalAllocatedMediumBlockSize);
    Inc(FastMM, MMState.TotalAllocatedLargeBlockSize);

    Memo1.Lines.Add(Format(' Memory %d%% %.2nm %s%.2nm / %.2nm / %.1nk records / %.1nk changes', [
      GStatus.dwMemoryLoad, Int64(GStatus.ullTotalVirtual - GStatus.ullAvailVirtual) / 1048576,
      IfThen(Mem < GStatus.ullAvailVirtual, '', '+'), Int64(Mem - GStatus.ullAvailVirtual) / 1048576,
      FastMM / 1048576, CDS.RecordCount / 1000, CDS.ChangeCount / 1000
    ]));
    Mem := GStatus.ullAvailVirtual;
  end;
begin
  Mem := 0;
  CDS := TClientDataSet.Create(Self);
  CDS.FieldDefs.Add('TEST1', ftString, 500);
  CDS.FieldDefs.Add('TEST2', ftString, 500);
  CDS.FieldDefs.Add('TEST3', ftString, 500);
  CDS.CreateDataSet;
  CDS.LogChanges := False;

  for var i := 1 to 25 do begin
    CDS.Append;
    CDS.FieldByName('TEST1').AsString := Random(MaxInt).ToString;
    CDS.FieldByName('TEST2').AsString := Random(MaxInt).ToString;
    CDS.FieldByName('TEST3').AsString := Random(MaxInt).ToString;
    CDS.Post;
  end;
  ShowState;

  for var i := 1 to 100000 do
    try
      CDS.RecNo := i mod {25} CDS.RecordCount + 1;
      CDS.Edit;
      CDS.FieldByName('TEST1').AsString := Random(MaxInt).ToString;
      CDS.FieldByName('TEST2').AsString := Random(MaxInt).ToString;
      CDS.FieldByName('TEST3').AsString := Random(MaxInt).ToString;
      CDS.Post;
      if i mod 5000 = 0 then
        ShowState;
    except
      on E: Exception do begin
        Memo1.Lines.Add(i.ToString + ' : ' + E.Message);
        ShowState;
        Break;
      end;
    end;
  ShowState;
end;