Is This Correct?

[Walt Decker]

A thread created with THREAD CREATE will automatically terminate when its parent process terminates, e.g., a dialog even though the thread has not completed it's task?

[Mike Doty]

True. http://www.powerbasic.com/support/pb...ghlight=thread

[Walt Decker]

Mike, that's what I thought; however, I think it depends on where the thread(s) w/as created. For example:

PBMAIN/WINMAIN creates window(s)
window calls intermediate process
intermediate process creates thread(s)

If the intermediate process has no way of knowing that the window has closed it will continue running as will the thread(s). Could produce a gpf somewhere along the line.

[Michael Mattias]

If the intermediate process has no way of knowing that the window has closed it will continue running as will the thread(s). Could produce a gpf somewhere along the line

Huh?

Threads are owned by processes. When the process dies, any owned threads are terminated, too... as shown in the doc I found in the post linked in this forum thread.

What happens in one process never affects what happens in threads owned by another process (unless you do some VERY deliberate things).

Attempts to access memory "owned" by a non-existent process give the same results as any other attempt to use unowned memory.... a protection fault with reason code 0x00000005.

MCM

[Mike Doty]

I just created a program where threads create threads and when
the main thread terminates they all go bye bye. I also say, huh.

If a second thread creates threads, the created threads are not terminated when the second thread finishes.

[Michael Mattias]

just created a program where threads create threads and when the main thread terminates they all go bye bye.

Expected.

If a second thread creates threads, the created threads are not terminated when the second thread finishes

Expected.

Threads do not own threads, processes own threads.

[Mike Doty]

Testing is good.

[Walt Decker]

I don't see any "Huh" about it.

You guys are saying exactly what I said above. It all depends on where the thread(s) w/ere created. However, if the program ends, all processes (sub programs, functions, threads) should end.

[Michael Mattias]

>Testing is good

I guess I just could not believe it: someone was in doubt, so they actually tried it to see what happens.

I can leave this world now, for I have been to the mountaintop, and have seen the promised land.

[Mike Doty]

Walt,
It does not depend upon where the threads were created.

[Walt Decker]

Yes, it does:

#PBFORMS CREATED V1.51
'------------------------------------------------------------------------------
' The first line in this file is a PB/Forms metastatement.
' It should ALWAYS be the first line of the file. Other
' PB/Forms metastatements are placed at the beginning and
' end of "Named Blocks" of code that should be edited
' with PBForms only. Do not manually edit or delete these
' metastatements or PB/Forms will not be able to reread
' the file correctly.  See the PB/Forms documentation for
' more information.
' Named blocks begin like this:    #PBFORMS BEGIN ...
' Named blocks end like this:      #PBFORMS END ...
' Other PB/Forms metastatements such as:
'     #PBFORMS DECLARATIONS
' are used by PB/Forms to insert additional code.
' Feel free to make changes anywhere else in the file.
'------------------------------------------------------------------------------

#COMPILE EXE
#DIM ALL

'------------------------------------------------------------------------------
'   ** Includes **
'------------------------------------------------------------------------------
#PBFORMS BEGIN INCLUDES
#IF NOT %DEF(%WINAPI)
  #INCLUDE "WIN32API.INC"
#ENDIF
#PBFORMS END INCLUDES
'------------------------------------------------------------------------------

'------------------------------------------------------------------------------
'   ** Constants **
'------------------------------------------------------------------------------
#PBFORMS BEGIN CONSTANTS
%IDD_DIALOG1 = 101
%IDC_BUTTON1 = 102
#PBFORMS END CONSTANTS
'------------------------------------------------------------------------------

'------------------------------------------------------------------------------
'   ** Declarations **
'------------------------------------------------------------------------------
DECLARE CALLBACK FUNCTION ShowDIALOG1Proc()
DECLARE FUNCTION ShowDIALOG1(BYVAL hParent AS DWORD) AS LONG
DECLARE CALLBACK FUNCTION ShowDIALOG2Proc()
DECLARE FUNCTION ShowDIALOG2(BYVAL hParent AS DWORD) AS LONG
DECLARE SUB Do_Nothing()
DECLARE THREAD FUNCTION A_Thread(BYVAL DWORD) AS LONG
#PBFORMS DECLARATIONS
'------------------------------------------------------------------------------

'------------------------------------------------------------------------------
'   ** Main Application Entry Point **
'------------------------------------------------------------------------------
FUNCTION PBMAIN()
  ShowDIALOG1 %HWND_DESKTOP
END FUNCTION
'------------------------------------------------------------------------------

'------------------------------------------------------------------------------
'   ** CallBacks **
'------------------------------------------------------------------------------
CALLBACK FUNCTION ShowDIALOG1Proc()

  SELECT CASE AS LONG CBMSG
    CASE %WM_INITDIALOG
      ' Initialization handler
      showdialog2(CBHNDL)
    CASE %WM_NCACTIVATE
      STATIC hWndSaveFocus AS DWORD
      IF ISFALSE CBWPARAM THEN
        ' Save control focus
        hWndSaveFocus = GetFocus()
      ELSEIF hWndSaveFocus THEN
        ' Restore control focus
        SetFocus(hWndSaveFocus)
        hWndSaveFocus = 0
      END IF

    CASE %WM_COMMAND
      ' Process control notifications
      SELECT CASE AS LONG CBCTL

      END SELECT
  END SELECT
END FUNCTION
'------------------------------------------------------------------------------
CALLBACK FUNCTION ShowDIALOG2Proc()

  SELECT CASE AS LONG CBMSG
    CASE %WM_INITDIALOG
      ' Initialization handler

    CASE %WM_NCACTIVATE
      STATIC hWndSaveFocus AS DWORD
      IF ISFALSE CBWPARAM THEN
        ' Save control focus
        hWndSaveFocus = GetFocus()
      ELSEIF hWndSaveFocus THEN
        ' Restore control focus
        SetFocus(hWndSaveFocus)
        hWndSaveFocus = 0
      END IF

    CASE %WM_COMMAND
      ' Process control notifications
      SELECT CASE AS LONG CBCTL
        CASE %IDC_BUTTON1
        CALL Do_Nothing
      END SELECT
  END SELECT
END FUNCTION

'------------------------------------------------------------------------------
'   ** Dialogs **
'------------------------------------------------------------------------------
FUNCTION ShowDIALOG1(BYVAL hParent AS DWORD) AS LONG
  LOCAL lRslt AS LONG

#PBFORMS BEGIN DIALOG %IDD_DIALOG1->->
  LOCAL hDlg  AS DWORD

  DIALOG NEW hParent, "main", 164, 103, 261, 121, %WS_POPUP OR %WS_BORDER OR _
    %WS_DLGFRAME OR %WS_CAPTION OR %WS_SYSMENU OR %WS_CLIPSIBLINGS OR _
    %WS_VISIBLE OR %DS_MODALFRAME OR %DS_3DLOOK OR %DS_NOFAILCREATE OR _
    %DS_SETFONT, %WS_EX_CONTROLPARENT OR %WS_EX_LEFT OR %WS_EX_LTRREADING OR _
    %WS_EX_RIGHTSCROLLBAR, TO hDlg
#PBFORMS END DIALOG

  DIALOG SHOW MODAL hDlg, CALL ShowDIALOG1Proc TO lRslt

#PBFORMS BEGIN CLEANUP %IDD_DIALOG1
#PBFORMS END CLEANUP

  FUNCTION = lRslt
END FUNCTION
'------------------------------------------------------------------------------

FUNCTION ShowDIALOG2(BYVAL hParent AS DWORD) AS LONG
  LOCAL lRslt AS LONG

#PBFORMS BEGIN DIALOG %IDD_DIALOG1->->
  LOCAL hDlg  AS DWORD

  DIALOG NEW hParent, "Create thread in other process", 164, 103, 261, 121, %WS_POPUP OR %WS_BORDER OR _
    %WS_DLGFRAME OR %WS_CAPTION OR %WS_SYSMENU OR %WS_CLIPSIBLINGS OR _
    %WS_VISIBLE OR %DS_MODALFRAME OR %DS_3DLOOK OR %DS_NOFAILCREATE OR _
    %DS_SETFONT, %WS_EX_CONTROLPARENT OR %WS_EX_LEFT OR %WS_EX_LTRREADING OR _
    %WS_EX_RIGHTSCROLLBAR, TO hDlg
  CONTROL ADD BUTTON, hDlg, %IDC_BUTTON1, "Create Thread", 65, 75, 65, 20
#PBFORMS END DIALOG

  DIALOG SHOW MODELESS hDlg, CALL ShowDIALOG2Proc TO lRslt

#PBFORMS BEGIN CLEANUP %IDD_DIALOG1
#PBFORMS END CLEANUP

  FUNCTION = lRslt
END FUNCTION

SUB Do_Nothing

LOCAL I AS LONG
LOCAL tHndl AS LONG

  FOR I = 1 TO 10
    THREAD CREATE A_Thread(I) TO tHndl
  NEXT I
  SLEEP 0
  DO
    DIALOG DOEVENTS 100
  LOOP

END SUB

THREAD FUNCTION A_Thread(BYVAL Q AS DWORD) AS LONG

LOCAL I AS LONG

  DO
    INCR I
    IF I MOD 100000 = 0 THEN
'      msgbox "this is thread " + str$(Q) + " at iteration " + str$(I)
    END IF
  LOOP
  MSGBOX "Thread " + STR$(Q) + " Closing"
END FUNCTION

As a matter of fact, the program will continue running although both windows are closed. You have to explicitly signal the creating process to close before the program will end. The message box in the thread do/loop is commented out simply to avoid creating a bunch of msgboxes.

[Mike Doty]

Closing a dialog is not ending the program.
The code locked up my machine. Is your second dialog supposed to be modeless?
Anyway, do you want me to debug it?
The second dialog caption says "Create thread in another process". That is not true.

This is not the correct way to check for a button click:

CASE %WM_COMMAND
      ' Process control notifications
      SELECT CASE AS LONG CBCTL
        CASE %IDC_BUTTON1
             IF CBCTLMSG = %BN_CLICKED OR CBCTLMSG = 1 THEN     'added this
                  CALL Do_Nothing
             END IF          'added this
      END SELECT

'endless loop

DO
    DIALOG DOEVENTS 100
LOOP

I'd start over on this one.

[Walt Decker]

Mike, it did exactly what it's supposed to do, i. e. illustrate a point and clarify a point in my own mind; something that was discussed in the windows programming category concerning whether an application will continue running if all the dialogs are closed.

Yes, the second dialog is supposed to be modeless, and no, there's no need to debug it.
The caption is true. The threads were created in another process.

[Mike Doty]

There is only 1 process.

[Michael Mattias]

>Closing a dialog is not ending the program
>...
>There is only 1 process.

I do believe, sir, you have acquired an excellent grasp of these concepts.

I am also pleased you are NOT writing Mr. Decker's code for him, instead guiding him to the correct solution.

This is better than sex.

MCM

[Walt Decker]

There is only 1 process.

Well, Mike, your definition of "process" is different than mine. There might be only milk factory but a myrid of processes handling the milk.

[Mike Doty]

Start task manager and look at the number of processes used by your program with any number of threads.

[Michael Mattias]

>Well, Mike, your definition of "process" is different than mine

When you are posting in a Windows' programming forum, the meaning of the word "process" is not subject to debate or personal preference.

MCM

[Mike Doty]

Speaking of PID's:

Did you know you can also suspend/resume a process?
In Task Manager:
Click View
Click Select Columns
Click PID (Process Identifer)

Download:
Wayne Diamond - Suspend/resume a process PID

http://www.powerbasic.com/support/pbforums/showthread.php?t=24023

You can now stop processes using the PID (at your own risk.)

[Cliff Nichols]

A thread created with THREAD CREATE will automatically terminate when its parent process terminates, e.g., a dialog even though the thread has not completed it's task?

I see this often, but can NOT explain it cause my tests show me I am wrong??? which leads me to "How can a thread be open if the process is closed????"

originally I set out to show MCM he was wrong, and in turn showed that I was wrong (although I can not explain why larger projects all point to a misuse of threads??? when closing a program

My Example below....and I tried to make it as "Sloppy" as I could, but each test comes back that the process exits

#COMPILE EXE
#DIM ALL
#INCLUDE "Win32Api.Inc"
GLOBAL LiveThread AS LONG
DECLARE CALLBACK FUNCTION ShowDIALOG1Proc()
DECLARE FUNCTION ThreadFunction(BYVAL X AS LONG) AS LONG
DECLARE FUNCTION ThreadFunction2(BYVAL X AS LONG) AS LONG

CALLBACK FUNCTION ShowDIALOG1Proc()
     LOCAL MyThread AS LONG

    SELECT CASE AS LONG CBMSG
        CASE %WM_INITDIALOG
            ' Initialization handler

        CASE %WM_NCACTIVATE
            STATIC hWndSaveFocus AS DWORD
            IF ISFALSE CBWPARAM THEN
                ' Save control focus
                hWndSaveFocus = GetFocus()
            ELSEIF hWndSaveFocus THEN
                ' Restore control focus
                SetFocus(hWndSaveFocus)
                hWndSaveFocus = 0
            END IF

        CASE %WM_COMMAND
            ' Process control notifications
            SELECT CASE AS LONG CBCTL
                CASE 100
     THREAD CREATE ThreadFunction(1) TO MyThread
     IF MyThread THEN LiveThread = %TRUE
MSGBOX FUNCNAME$ + $CR + "Thread Created = " + STR$(MyThread) + $CR + "Live Thread = " + STR$(LiveThread)

            END SELECT
    END SELECT
END FUNCTION

FUNCTION PBMAIN () AS LONG
     LOCAL hDlg AS LONG
     DIALOG NEW %HWND_DESKTOP, "Test Dialog", 0,0, 100, 100, %WS_SYSMENU TO hDlg
CONTROL ADD BUTTON, hDlg, 100, "Set Ok to close", 5, 5, 10, 50
     DIALOG SHOW MODAL hDlg, CALL ShowDIALOG1Proc
END FUNCTION

FUNCTION ThreadFunction(BYVAL X AS LONG) AS LONG
     LOCAL LoopCount AS LONG
     LOCAL MyThread2 AS LONG
     DO
          LoopCount = LoopCount + 1
          IF MyThread2 = 0 THEN THREAD CREATE ThreadFunction2(1) TO MyThread2
     LOOP WHILE LiveThread = %TRUE
MSGBOX FUNCNAME$ + $CR + "I looped" + STR$(LoopCount) + " times"
END FUNCTION

FUNCTION ThreadFunction2(BYVAL X AS LONG) AS LONG
     LOCAL LoopCount AS LONG
     DO
          LoopCount = LoopCount + 1
     LOOP WHILE LiveThread = %TRUE
MSGBOX FUNCNAME$ + $CR + "I looped" + STR$(LoopCount) + " times"
END FUNCTION

Makes me wonder what else in larger programs can hold a program open till satisfied???? when the parent process is closing?