How to achieve true 100% multi-threading in VB. OLD THREAD

Quote:

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Originally posted by jian2587
I kept thinking about how to put those stuffs in a DLL, so we can
just create a thread without writing much codes.

Now tinkering with some of my ideas, will post it when it's working
rite!

I'm using apartment threading, but since it's a DLL...well...I'll try
to put SetTimer in use as well, let's see if it works.:)

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You are going to create the ability to multithread by using a DLL and the SetTimer API??? Errrrrr...the DLL runs in the same thread as the thread it is created in...:confused:
I know you can almost simulate multithreading with an ActiveX EXE and a timer...but a DLL?!

Woka

I know clearly what I'm doing.
I've also thought that they would run in the very same thread.
and what's more that's a DLL......don't u see how doubtful am I
when I mentioned it? But what I am going to say is that I'm trying
to use various methods to put things up and running...and now
i'm still testing stuffs...and still failing...but i'm not giving up...

probably i'll found a method that'll put it in another thread...
btw, vb6's a crappy thing...though sometimes useful

and juz w8 4 my good news:)......or may be bad news:(

That is quite a piece of work Woka, Great Job!

The 'Switch To/Retry' thing only happens if you run it from the IDE- for whom ever mentioned it earlier.

Quote:

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Originally posted by jian2587

probably i'll found a method that'll put it in another thread...
btw, vb6's a crappy thing...though sometimes useful

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If that's how you feel then take some advice and keep your ignorance off the VB Forums.

Woka's code is awesome, plain and simple.

If it is so difficult and buggy to create threads with VB then why dont we create a dll in c++ and use it for creating threads ?

Has anybody seen such an example ?
I mean we could use VB for the GUI and then call the c++ dll to do the thread jobs.

If you have seen such an example please tell it.

Because if you're a VB developer - you're developing in VB, not C++

1st off, it's not buggy and hard to do it in VB. My code does it perfectly, even if I do say so myself. Up untill now it was "impossible", or if it wasn't then I ain't seen it.

The problem with your solution is that people like me, who don't like computers and only use them to pay my morgage, do not know C++ or Java, or web or anything else about them to be fair :(
I know VB. I would say I am very compitent at VB, but anything else I am a muppet, and don't mind admitting it. I have no intention of learning C++, why would I want to?

My way of thinking, since I was about 13 has been "Does it get me a job?...No...Then why should I learn it?"...that frame of mind as served me well over many many years, so yo can't critise it, although I know it may not be everyones cup of tea.

Also, this would involve having C++ on my computer, which I don't :( If I was a computer genius, which I am not, and computers were my soul and life then yes, I wouldn't do it in VB and would completely agree with you.

Do you see my point?

Sorry if I seem to have been ranting but I am pissed off, having a bad week :(

Everyone smile and say CHEEEEESSSEEE JENNY :D

Woofy Woka :)

Well my point of view is that you are a computer programmer/scientist. You have to know some other languages too. The language is only the tool to implement algorithms.
Since you know so good VB it will be not hard for you to
learn the basics of C++.

Anyway i found a link:
http://www.codeproject.com/useritems/VBThread.asp

for anyone interested.It says it will create threads for vb com objects via the CreateThread api by using a dll written in c++.

by the way what about the guy that had an error with your program while he was testing it on a slow computer ?
Is it ok ?

I think your code is great but i want to be sure that it is working on all platforms.

cheers
alexandros

Woka,
i dont like to be denied, for I've to try it myself and proof that it
can either be done or not. and i'm not limiting myself with the
methods I discussed earlier, my main objective is creating a COM
DLL that could allow VB to thread, so there can be tons of ways to
achieve that. I myself accept the fact that VB has some
limitations, particularly in this area. Though your advice to me is
good, I've always like to see the things for myself. Even if it fails,
atleast, I know how it works and why it fails, entirely built upon
my true self-experience.
My post on creating that threading DLL, technically speaking, if
based on the common ideas of methods you told me that would
not work, it will not work, and I accept that fact.
For years I visited this forum, tons of people had said that VB
does dangerous threadings, but somehow you have done it.

After all, technology is about breakthrough, isn't it?:)

I completely agree.
That's how I have learnt VB.
Someone posts some code and I strip it down, tear it apart to see how it works. I will also critisise the code, or ask silly questions about it, knowing the answers full well, but it starts a debate and I usually learn something new from peoples comments.
Then a few months later I will find another snippet of code, nothing to do with the 1st, but think "hey, if I insert that in here, and this there, and change this to this that...and...damn it doesn't work/YES! That works a treat."...That's how I learnt VB, no vb books and no courses, most of the code is from VBF :D

alexandros: I am a VB developer. I have no intention of learning C++. And, like I said it helps if we have C++ on our computers, so how do you expect me to learn it??? :D
I know VB and SQL Server (to a certain extent) and that's it. There is literally no need for me to learn C++ or any other language for that matter. VB does everything I want it to, I have not needed to multithread up until now as I have developed a "new" way for client server applications to communicate via TCP/IP which replaces the need for DCOM/COM+. Again there is nothing on the web for this, and the code is way more complicated than this multithreading code. This code is "unique" and requires VB to multithread to achieve what I have done.

The CreateThread API is only unstable in VB, which is why you can achieve this using a DLL compiled using C++. But then we are back to my orginal comments about C++.

Woofa

Anyway i tried another thread application that uses c++ to download files and it crashed all the times !!!http://www.codeproject.com/internet/retrievehttp.asp

VB.NET supports multithreading ;)

Quote:

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Originally posted by Wokawidget
Everyone smile and say CHEEEEESSSEEE JENNY :D

Woofy Woka :)

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:D CHEEEEESSSEEE JENNY

Woka,
I've two ideas.

First idea:
wut do u think about having a multithreading service built using
VB6?
wut I mean is create an ActiveX exe project which will provide a
run-time interface for us to create a new thread through
GetObject. Quite near to a DLL one, though.

Second idea:
Create a process, and use CreateRemoteThread or whatsoever,
and we put our object there. I don't know if this actually works.
For that process, we might put a dummy program there.

Quote:

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Originally posted by kleinma
VB.NET supports multithreading ;)

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You betcha ;)

I'm still learning VB.NET, but am almost about to reach that chapter.


















Then I'll skip it. :afrog:

Good ideas, but I am afraid they may nod be possible :(
Your have to remember that the multithread involves 2 projects. A DLL proxy, which converts your functions to the correct UDT data that can be passed, and the ActiveX EXE which reverses this process.
No-one has been able to do this over x many years. It's not going to happen over night. Maybe in 2-3 years time somone will figure it out.
The problem is that each theading object u want is going to be unique with different return values, events, subs and functions :(

I am OK at VB, I am not an elite coder, which I fell you may have to be to implement what you are asking.

Keep trying though ;)

Woka

Woka: This is pretty spiffy. Problem is that threads in VB can't really be called threads, though this program fakes it well. VB threads are almost totally separate processes, each only looking in its own little address space, that just happen to be indexed with the same process ID. That you have to go through all the PostMessage and ReadProcessMemory nonsense in indicative of that. With real threads, they should be running on the _same_ address space and so being able to reference the same global variables and classes, requiring only the setting and releasing of mutexes to keep things running orderly.

Yes, that is absolutely correct. However, this isn't possible using VB I am afraid. However. Merrion has pointed me in the direction of creating a memory space that both theads have access to...however, this I believe, well in my head anyways, this is only theory at this moment in time.
Will have a look into...

Woka

WokaWidget ....
Which of the many downloads is the best one to get? and which installation instructions should I follow? My DSL got fried in the LA fires and will be down for many weeks ... and I hate dial-up downloading!

The 4th post in this thread.
The 1st post has a VERY simple demo attached.
The 4th post has an attached zip file that is a more realistic demo.
Also, follow the instructions in the 4th post.

Sorry to hear about the fires :(Hope the DSL was the only thing that got damaged...you yanks never do things by halves do you :D Hahahaha You can't just have a small forrest fire...noooooo...you have to have an absolute monster that destroys everything :) Sorry, shouldn't be joking about it :(

Give us a shout if you need anything else.

Woka

Would a simple approach be to have your main app, and it creates a few instances of an activex control or class or whatever you want.
Now, you give to it the address of various functions in your application, and it can then, through the use of CallWindowLong (If I remember the API name correctly!) call those functions as they need to...

Look, you must know by now that I don't do simple :D

Hahahaha...

Is CallWindowLong like an API version of CallByName?
Wouldn't this be like using SendMessage, in the sense that it won't return execution until the function I have called is finished?

Can't find that API in APIGuide :(

Woka

Sorry. I keep getting it wrong, its this :

VB Code:

Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

You call it, but it doesn't wait for a response. It just does its thang and then that's that.
Well from what I remember anyway!

I have some sample code at home for calling a function by its address. I can show it to you tonight.

Cool. Will be on laterz tonight, around 9pm'ish.
However, you will still have to read the parameters from the client processes memory.
My exmples use the uMsg to tell the app what function/sub to execute, and the lParam as the memory location for the datastruct UDT. I would still have to pass the lParam with this API...

I am failing to see how this can be easier??? :(

Mind you, I have been doing documentation for the last 4 ****ing days and my head is fried...plus I have other things on my mind as you well know ;)

Woka

Well the only time I've used this, it was to call a parameterless function - basically to kick off another function.
And if I remember correctly, I think duncan said that that's only for code inside the same process's memory space.

Don't remember though. I'll have a fiddle tonight.
... speaking of which, and what's on your mind, ... ;)

Maybe for a paramater-less function this may be ok, but I feel that using Postmessage and the uMsg to determind what function to run may be a better method in the long run. The code will be almost identical, yet using Postmessage gives you more functionality and makes the app easier to maintain.

Am still intregued mind you...:)

Woka

Here's the code. Basically I have 3 screenshots built into one of my applications. They're compressed into the VB code.
I have a window in the app taht the user might want help on.
On it is this :

VB Code:

Private Sub lblLink_Click(Index As Integer)
    Dim imgHandle As Long: imgHandle = -1
    Dim strHeading As String, strContent As String
    Set callingForm = Me
    Select Case True
        Case Index = 0 Or Index = 1:
            [b]imgHandle = getAddressOf(AddressOf modScreenShot1.getFile)[/b]
            strHeading = "Create & Share Folder"
            strContent = STR_DOC_1
        Case Index = 3:
            [b]imgHandle = getAddressOf(AddressOf modScreenShot3.getFile)[/b]
            strHeading = "Copy Files"
            strContent = STR_DOC_2
        Case Index = 4:
            [b]imgHandle = getAddressOf(AddressOf modScreenShot2.getFile)[/b]
            strHeading = "Modify User Scripts"
            strContent = STR_DOC_3
    End Select
    makeDocumentationWindow strHeading, strContent, imgHandle
End Sub

Then the makeDocumentationWindow function is declared in a code module as follows :

VB Code:

Public Sub makeDocumentationWindow(ByVal strTitle As String, ByVal strContent As String, Optional imgHandle As Long = -1)
    With frmDoc
        .Hide
        .Caption = .Caption & strTitle
        .lblShowImage.Visible = Not imgHandle = -1
        .lblShowImage.Enabled = .lblShowImage.Visible
        .imgImageHandle = imgHandle
        With .rtbText1
            .Text = strTitle
            .Find (strTitle)
            .SelBold = True
            .Text = .Text & vbCrLf & vbCrLf & strContent
            .SelStart = Len(strTitle)
            .SelLength = Len(Mid(.Text, InStr(.Text, strTitle) + .SelStart))
            .SelBold = False
            .SelStart = 0
        End With
        centerMe frmDoc: .Show
        SetTopmost frmDoc, True
        .cmdClose.SetFocus
    End With
End Sub

The frmDoc window has the following code. This form is what actually displays the help information, and gives the user what looks like a hyperlink to generate the image.

VB Code:

Option Explicit
 
Public imgImageHandle As Long
 
Private Declare Function CallWindowProc& Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc&, ByVal hWnd&, ByVal Msg&, ByVal wParam&, ByVal lParam&)
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (lpvDest As Any, lpvSource As Any, ByVal cbCopy As Long)
 
Private Sub cmdClose_Click()
    Unload Me
End Sub
 
Private Sub Form_Unload(Cancel As Integer)
    If callingForm Is frmA_1_Splash2 Then frmA_1_Splash2.cmdNext.SetFocus
End Sub
 
Private Sub lblShowImage_Click()
    MousePointer = vbHourglass
[b]    CallWindowProc imgImageHandle, 0, 0, 0, 0[/b]
    imagesUsed(UBound(imagesUsed)) = tempPathToUse
    ReDim Preserve imagesUsed(UBound(imagesUsed) + 1)
    SetTopmost Me, False
    [i]StartDoc tempPathToUse[/i]
    MousePointer = vbNormal
End Sub

Now, I have attached modScreenshot3 so that you can see what getFile() does.

You'll see that I'm using a module level String variable - tempPathToUse (italicized above).
That variable is populated inside getFile() in modScreenshot1, modScreenshot2 and modScreenshot3.

The screenshot modules are generated using this code :
http://www.vbforums.com/showthread.p...hreadid=195896

Arggg where was this fabulous code about a year ago when I was trying to write a FTP Client in VB. I gave up when I got to testing it and couldn't download more than one file and do stuff in the program simultaneously even with doevents pasted everywhere! I knew multithreading was what I needed and at the time the only way I knew of to do it was unreliable.

hmmm now to find that old code and restart that project! =)

Hey Woka, I have two questions for you.

The first is just to make sure I'm right about something... the MyThread.exe is where I would change to my forms and functions for whatever I need multi-threaded and the thread proxy I would just have to change to transfer the approriate variables and stuff correct?

And also I noticed in the vbtools2 a memory thing, If I'm not mistaken couldn't I use this to accomplish what I asked in my other post about reading memory?

Steven

Errr...Yes. U will also need to update the UDT's in the MyThread project as well as the ThreadProxy project.

What was your memory question? What memory are you trying to read?

The code was lurking around as a concept in my drug fueled brain...sorry :D

Well the thing is, I'm a total n00b when it comes to tampering with the memory. I've never tried to tackle it yet. But I want to be able to take a running application and get everything it has in the memory if that is even possible?

I havn't looked at your memory code much but it seems that it might in fact be able to do this?

I think your best bet here is to chat to Merrion, he's the god of all that type of programming :D

Woka

In thiis project how can i get the ThreadUI to destroy the thread once the search has finished?

many thanks

Woka

Nice work.

Hey a while back in the this thread you said that you don't like to use GOTO statments. If that is the case how do you make a jump over a chunk code if you want to skip it for one reason or another? This would be in a situation where if conditions are met you want to skip some code but not exit the sub or for etc...

I've been able to arrange if statements so that they do the trick sometimes but some times I just can't do it with ifs without nearly doubling the amount of code needed to get the job done. Is there some other method that you use in these situations?

Thanks

David

Quote:

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Originally posted by David RH
Woka

Nice work.

Hey a while back in the this thread you said that you don't like to use GOTO statments. If that is the case how do you make a jump over a chunk code if you want to skip it for one reason or another? This would be in a situation where if conditions are met you want to skip some code but not exit the sub or for etc...

I've been able to arrange if statements so that they do the trick sometimes but some times I just can't do it with ifs without nearly doubling the amount of code needed to get the job done. Is there some other method that you use in these situations?

Thanks

David

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I'm not trying to be sarcastic here but If/Then/Else.

Edit: I see you've tried that. Can you post some code (probably best done in a different thread) where you need help eliminating GoTos?

I am lost. What have Goto's got to do with multithreading?
I don't use goto's...well very slightly in error handling.

Nosh...?! I thought we sorted this problem out last week??? :confused: Zzzzzzzzzzzzzzzz I am tired.
After the search loop has finished just do:

VB Code:

UnLoad Me

And that should do the trick.

Woka

Well ...

Back in the middle of the ton of posts to this thread you told someone no thanks to their code donation because you don't use GOTO statements. So I was wondering if you had some special way to handle a jump when you can't get an If...Then... Else statement to work without writing a whole lot of extra code (sometimes nearly double).

I probably shouldn't be responding to this post this late at night when I'm tired as I might respond in kind But I'm curious about a possible alternative way of doing something more efficiently.

Sorry to have bothered you.

David

U can always get an IF THEN statement to work. I only use Goto's for err handlers...

VB Code:

Dim Sub Woof()
On Error Goto ErrHandler:
   'Code to handle sub
   Exit Sub
ErrHandler:
   'Code to handle error
End Sub

They arn't classes as proper goto's really.

Why can't you get the IF THEN statement to work??? You could split your code into sperate smaller subs so that you don't have to replicate it.

Woka

I have created a new demo project.
Full working 3 tiered app that uses multithreading to monitor DB tables and thus not affecting the performace of the client while the Db is being queried for changes.

http://www.vbforums.com/showthread.p...postid=1606760

Have fun.

Woof

The way I see this is that the post message API is being used to post a message and execution then continues. The thread performs the processing and then sends a message back to the calling process.

What I want to do is to create a system that uses multiple access databases to seach for a record in paralell petween all databases. This means that a single thread would search each database. Question is, how would I return the result? Use property bags?? Is there a way that I can just use the address of a recordset to return the info? Whichever is easiest....

Also, is there a way that this example can done using fewer files???