Runtime Thread Access Violation Errors - multithreading

Question

My idea is to download all files from a folder and subfolders in a stringlist.
Next I use the SHGetFileInfo function to retrieve the names and type the date and links from the files to load into my Access database.
My application works fine, but when I use a large folder that contains hundreds of files, it blocks what I need to use the thread.
When I use the thread and my table is empty, it displays error messages, but the second time when my table contains records it shows no problem.
Procedure of searche
procedure FileSearche(const PathName: string; var lstFiles: TStringList);
const
FileMask = '*.*';
var
Rec: TSearchRec;
Path: string;
begin
Path := IncludeTrailingBackslash(PathName);
if FindFirst(Path + FileMask, faAnyFile - faDirectory, Rec) = 0 then
try
repeat
lstFiles.Add(Path + Rec.Name);
until FindNext(Rec) <> 0;
finally
FindClose(Rec);
end;
if FindFirst(Path + '*.*', faDirectory, Rec) = 0 then
try
repeat
if ((Rec.Attr and faDirectory) <> 0) and (Rec.Name <> '.') and
(Rec.Name <> '..') then
FileSearche(Path + Rec.Name, lstFiles);
until FindNext(Rec) <> 0;
finally
FindClose(Rec);
end;
end;
Procedure of thread
//--------------------------------------------------------------
{ debloc }
procedure debloc.execute;
var
icn: HICON;
SHFileInfo: TSHFileInfo;
SearchRecord: TSearchRec;
Size, I: Integer;
lstFiles: TStringList;
State: SHELLSTATE;
lien, path: string;
isEmpty : boolean;
begin
// to request windows to display the extension of all files
SHGetSetSettings(State, SSF_SHOWEXTENSIONS, false);
State.Data := State.Data or SSF_SHOWEXTENSIONS;
SHGetSetSettings(State, SSF_SHOWEXTENSIONS, True);
SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_FLUSHNOWAIT, nil, nil);
// for select folder
if SelectDirectory('Choisi un dossier ', ' ', path) then
Lien := IncludeTrailingPathDelimiter(path) else exit;
isEmpty := IsDirectoryEmpty(path) ;
// To verify that the folder is not empty
if isEmpty = false then
Begin
if MessageDlg('Remarque Le dossier :'+#13+path +#13+'est vide il n y pas des fichiers à importer', mtInformation,
[mbOK], 0, mbOK) = mrOk then
exit;
End;
// To verify that the folder is not folder systeme
if
(Lien = IncludeTrailingPathDelimiter(SpecialFolder(CSIDL_WINDOWS)))
or (Lien = IncludeTrailingPathDelimiter(SpecialFolder(CSIDL_SYSTEM)))
or (Lien = IncludeTrailingPathDelimiter(SpecialFolder(CSIDL_PROGRAM_FILES)))
or (Lien = IncludeTrailingPathDelimiter(SpecialFolder(CSIDL_PROGRAM_FILESX86)))
or (Lien = IncludeTrailingPathDelimiter(SpecialFolder(CSIDL_MYPICTURES)))
or (Lien = IncludeTrailingPathDelimiter(SpecialFolder(CSIDL_PROGRAM_FILES_COMMONX86)))
or (Lien = 'C:\')
then
begin
// ShowMessage(Lien+#13+'Erro, Les dossiers système sont ignoré pour votre sécurité');
if MessageDlg(Lien+#13+'Attention, Pour des raison de sécurité les dossiers système sont ignoré ', mtWarning,
[mbYes], 0, mbYes) = mrYes then
exit;
end
else
begin
//To list the files in the StringList
begin
lstFiles := TStringList.Create;
FileSearche(lien, lstFiles);
end;
if lstFiles.Count > 0 then
for I := 0 to lstFiles.Count - 1 do
begin
//To get the name, type, date, links of all files
SHGetFileInfo(PChar(lstFiles[I]), 0, SHFileInfo, SizeOf(TSHFileInfo),
SHGFI_TYPENAME or SHGFI_DISPLAYNAME or SHGFI_SYSICONINDEX or
SHGFI_ICON);
FindFirst(lstFiles[I], 0, SearchRecord);
Size := SearchRecord.Size;
//To fill the Field of the table
Form1.FDTable1.Edit;
Form1.FDTable1.Insert;
Form1.FDTable1.FieldByName('nom_file').ASSTRING := (SHFileInfo.szDisplayName);
Form1.FDTable1.FieldByName('type_file').ASSTRING := (SHFileInfo.szTypeName);
Form1.FDTable1.FieldByName('size_file').ASSTRING := (GetFileSizeAsString(Size));
Form1.FDTable1.FieldByName('date_time_file').ASSTRING :=
(DateTimeToStr(FileDateToDateTime(SearchRecord.Time)));
Form1.FDTable1.FieldByName('lien_file').ASSTRING :=
(ExtractFilePath(lstFiles[I]));
Form1.ProgressBar1.Max := Form1.FDTable1.RecordCount;
Form1.ProgressBar1.Position := Form1.FDTable1.RecordCount;
end ;
Form1.FDTable1.Post;
Form1.FDTable1.First;
Form1.StatusBar1.Panels[0].Text := 'Nombre d"enregistrements: ' +
IntToStr(Form1.FDTable1.RecordCount);
// to request windows to hide the extension of all files
SHGetSetSettings(State, SSF_SHOWEXTENSIONS, false);
State.Data := State.Data and ($FFFFFFFF xor SSF_SHOWEXTENSIONS);
SHGetSetSettings(State, SSF_SHOWEXTENSIONS, True);
SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_FLUSHNOWAIT, nil, nil);
// procedure to rearrange the automatic columns
SetGridColumnWidths(Form1.dbgrid1);
Application.ProcessMessages;
end;
end;
to execute thread
procedure TForm1.Button1Click(Sender: TObject);
BEGIN
with debloc.Create do
FreeOnTerminate:=true;
END;
When I use the thread and the table is empty, it displays the error message
violation d'accès à l'adresse 00732BB1
But the second time, when my table is saved, it is not a problem.
Note: Despite this code that annoys me, the application works as even
another thing I do not know how to stop the thread when the folder is very big. I close the application for the stop.

Answer 1

I solved the problem by replacing the dbgrid component with the listview component
procedure debloc.transfertdata;
var
Myitem : TListItem;
MyColumn : TListColumn;
begin
ListView1.Items.Clear;
ListView1.Columns.Clear;
MyColumn:= ListView1.Columns.Add;
MyColumn.Caption:= 'Nom' ;
MyColumn.Width := -1;
MyColumn:= ListView1.Columns.Add;
MyColumn.Caption:= 'Type' ;
MyColumn.Width := -1;
MyColumn:= ListView1.Columns.Add;
MyColumn.Caption:= 'Taille' ;
MyColumn.Width := -1;
MyColumn:= ListView1.Columns.Add;
MyColumn.Caption:= 'Date de modification' ;
MyColumn.Width := -1;
MyColumn:= ListView1.Columns.Add;
MyColumn.Caption:= 'Lien' ;
MyColumn.Width := -1;
FDTable1.First;
while not FDTable1.Eof do
begin
ListView1.Items.BeginUpdate;
Myitem := ListView1.items.Add;
Myitem.Caption:= FDTable1.FieldByName('nom_file').ASSTRING;
Myitem.SubItems.Add(FDTable1.FieldByName('type_file').ASSTRING) ;
Myitem.SubItems.Add(FDTable1.FieldByName('size_file').ASSTRING) ;
Myitem.SubItems.Add(FDTable1.FieldByName('date_time_file').ASSTRING) ;
Myitem.SubItems.Add(FDTable1.FieldByName('lien_file').ASSTRING) ;
FDTable1.Next;
ListView1.Items.EndUpdate;
end;
end;
and in the thread I added
Synchronize(transfertdata);