Application freezes when changing windows.

Question

The code below forces the application to freeze when the focus changes from Edit1 to Edit2 after creating the stream.

Steps to play:

• Click the "Create Topic" button
• Switch focus between Edit1 / Edit2.

I think that creating an ADO object inside a thread causes the application to freeze.

Does anyone have an idea what the exact problem is?

Note. I think the problem occurs when changing the default input language. Win xp - Text Services and Input Languages ​​dialog box - The default input language.

Same issue as:

http://social.msdn.microsoft.com/Forums/en/vcgeneral/thread/1d27c2ad-7ef1-45e9-b9af-6bfb458c1165

pas file

unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, ADODB, SyncObjs, ActiveX, ComObj, Menus, StdCtrls; type TMyThread = class(TThread) private FEvent : TEvent; adoConnection : TADOConnection; protected procedure Execute; override; public constructor Create(ASuspended : boolean); destructor Destroy; override; end; TForm1 = class(TForm) Edit1: TEdit; Edit2: TEdit; Button1: TButton; procedure FormCreate(Sender: TObject); procedure FormClose(Sender: TObject; var Action: TCloseAction); procedure TextEdit1Enter(Sender: TObject); procedure TextEdit2Enter(Sender: TObject); procedure Button1Click(Sender: TObject); private { Private declarations } public { Public declarations } MyThread : TMyThread; end; var Form1: TForm1; implementation {$R *.dfm} { TMyThread } constructor TMyThread.Create(ASuspended: boolean ); begin inherited Create(ASuspended); FEvent := TEvent.Create(nil, false, false, 'test' ); end; destructor TMyThread.Destroy; begin FreeAndNil(FEvent); inherited; end; procedure TMyThread.Execute; begin CoInitializeEx(nil, COINIT_MULTITHREADED ); try adoConnection := TADOConnection.Create(nil); FEvent.WaitFor(INFINITE); adoConnection.Free; finally CoUnInitialize; end; end; procedure TForm1.Button1Click(Sender: TObject); begin MyThread.Resume; end; procedure TForm1.TextEdit1Enter(Sender: TObject); begin LoadKeyboardLayout(PChar(IntToHex(1081, 8)), KLF_ACTIVATE); end; procedure TForm1.TextEdit2Enter(Sender: TObject); begin LoadKeyboardLayout(PChar(IntToHex(1043, 8)), KLF_ACTIVATE); end; procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction); begin MyThread.FEvent.SetEvent; MyThread.Terminate; FreeAndNil(MyThread); end; procedure TForm1.FormCreate(Sender: TObject); begin MyThread := TMyThread.Create(true); end; end. 

form file

 object Form1: TForm1 Left = 0 Top = 0 Caption = 'Form1' ClientHeight = 115 ClientWidth = 147 Color = clBtnFace Font.Charset = DEFAULT_CHARSET Font.Color = clWindowText Font.Height = -11 Font.Name = 'Tahoma' Font.Style = [] OldCreateOrder = False OnClose = FormClose OnCreate = FormCreate PixelsPerInch = 96 TextHeight = 13 object Edit1: TEdit Left = 8 Top = 8 Width = 121 Height = 21 TabOrder = 0 Text = 'Edit1' OnEnter = TextEdit1Enter end object Edit2: TEdit Left = 8 Top = 35 Width = 121 Height = 21 TabOrder = 1 Text = 'Edit2' OnEnter = TextEdit2Enter end object Button1: TButton Left = 8 Top = 62 Width = 121 Height = 45 Caption = 'Create Thread' TabOrder = 2 WordWrap = True OnClick = Button1Click end end 

Answer 1

I decided.

In the pas file, change the line

  CoInitializeEx(nil, COINIT_MULTITHREADED ); 

to

  CoInitializeEx(nil, COINIT_APARTMENTTHREADED ); 

and

  FEvent := TEvent.Create(nil, false, false, 'test' ); 

to

  FEvent := TEvent.Create(nil, false, false, 'test', true );