Multi-thread download (idhttp)

The younger brother wrote a multi-thread download Program There are always signs of an endless loop, but I think it may be a deadlock. However, an error occurs during one-step tracking:
Unit indymthread;

Interface

Uses
Windows, messages, sysutils, variants, classes, graphics, controls, forms,
Dialogs, stdctrls, comctrls, idbasecomponent, idcomponent,
Idtcpconnection, idtcpclient, idhttp;

Type
Tform1 = Class (tform)
Btndowload: tbutton;
Btncancel: tbutton;
Edturl: tedit;
Label1: tlabel;
Redtmess: trichedit;
Idhttp1: tidhttp;
Procedure btndowloadclick (Sender: tobject );
Procedure formcreate (Sender: tobject );
Procedure formdestroy (Sender: tobject );
Private
{Private Declarations}
Public
{Public declarations}
End;
Tthreadload = Class (tthread)
Private
{Private declatation}
M_surl: string;
Protected
{Protected declaration}
Procedure GetFile (VAR sfilename: string );
Procedure reditadd;
Procedure execute; override;
Public
{Public declarations}
RedT: trichedit;
Constructor create (bwait: Boolean; const URL: string );

// Destructor destroy; override;
End;
VaR
Form1: tform1;
M_arrayimage: array [0 .. 4] of string;
G_ I: integer;
Criticalsec: trtlcriticalsection;
Implementation

{$ R *. DFM}
Procedure tthreadload. GetFile (VAR sfilename: string );
VaR
I: integer;
Begin
For I: = 0 to 4 do
Begin
If m_arrayimage [I] = ''then continue;
Sfilename: = m_arrayimage [I];
M_arrayimage [I]: = '';
Exit;
End;
End;

Procedure tthreadload. reditadd;
Begin
RedT. lines. append ('saving ');
End;
Procedure tthreadload. Execute;
VaR

Idhttp2: tidhttp;
File_name: string;
Streamfile1: tmemorystream;
Begin

While not terminated do
Begin
Entercriticalsection (criticalsec); // enter the critical section
Try
GetFile (file_name );
Idhttp2: = tidhttp. Create (NiL );
Try
Streamfile1: = tmemorystream. Create;
Try
Idhttp2.head (m_surl );
Idhttp2.get (m_surl, streamfile1 );
Streamfile1.savetofile ('d: \ '+ file_name );
Finally
Streamfile1.free;
End;
Finally
Idhttp2.free;
End;
// Synchronize (reditadd );
Finally
Leavecriticalsection (criticalsec );
End;
If file_name = ''then exit;
End; // begin

End;

Procedure tform1.btndowloadclick (Sender: tobject );
VaR
I, K: integer;
Threadarray: array [0 .. 4] of tthreadload;
Begin
For I: = 0 to 4 do
Begin
Threadarray [I]: = tthreadload. Create (true, edturl. Text + '/' + m_arrayimage [I]);
Threadarray [I]. RedT: = redtmess;
End;
For K: = 0 to 4 Do threadarray [K]. Resume;
End;

Constructor tthreadload. Create (bwait: Boolean; const URL: string );
Begin
Inherited create (bwait );
M_surl: = URL;
End;

{Destructor tthreadload. Destroy;
Begin
Inherited destroy;
End ;}

Procedure tform1.formcreate (Sender: tobject );
Begin
M_arrayimage [0]: parameter 'aa.bmp ';
M_arrayimage [4]: Invalid '4.jpg ';
M_arrayimage [2]: '1.jpg ';
M_arrayimage [3]: Invalid '2.jpg ';
M_arrayimage [1]: '3.jpg ';
G_ I: = 0;
Initializecriticalsection (criticalsec)
End;

Procedure tform1.formdestroy (Sender: tobject );
Begin
Deletecriticalsection (criticalsec );
End;

End.
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An error message is generated during Delphi's single-step tracking. Sometimes, the entire Delphi will die.
Drop


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