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Multithreading in VB6
Posted on 2002-04-18
Does anyone know how to do multithreading in VB6? For example, if I want to call a public function Process1()during form load, I want the form keep loading without waiting on Process1() to finish. Actually, I have a case the Process1() will be running during whole run time. It is like sth below:
Public Function Process1(arg1 as String)
do while True
......
loop
End Function
So, is there a way to use multithreading for this? I'd like to use it inside of the code, instead of creating an ActiveX.
Working sample code needed please.
Thanks!
hxia
Public Function Process1(arg1 as String)
do while True
......
loop
End Function
So, is there a way to use multithreading for this? I'd like to use it inside of the code, instead of creating an ActiveX.
Working sample code needed please.
Thanks!
hxia
[X]
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It will be hard for a VB6 app to get multi threading. BTW, VB.net supports it natively.
have a look at
http://www.desaware.com/articles/threadingL3.htm
http://www.desaware.com/articles/Waitingl3.htm
have a look at
http://www.desaware.com/articles/threadingL3.htm
http://www.desaware.com/articles/Waitingl3.htm
Some links on multithreading in VB
http://planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=26900&lngWId=1
http://planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=24672&lngWId=1
http://planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=14479&lngWId=1
I haven't really looked at these but take a look and see...
Cheers...
Ber...
http://planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=26900&lngWId=1
http://planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=24672&lngWId=1
http://planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=14479&lngWId=1
I haven't really looked at these but take a look and see...
Cheers...
Ber...
1. In Form_Load start your "long task" asynchronously.
2. In the loop in Process1() add enough DoEvents lines (e.g. 10 DoEvents per second).
For 1 you'll need a timer. To prevent reentering Process1() or to signal task has finished, you'll need a flag (Boolean variable).
' in Form_Load
ReadSomething ...
Timer1.Enabled = True ' this will start Process1
DoSomething ...
Show
Refresh
' in Timer1_Timer
Timer1.Enabled = False
If bExecuting Then Exit Sub
bExecuting = True ' set flag, defined in a module or form
Call Process1()
bExecuting = False ' reset flag
' in Process1
Public Function Process1(arg1 as String)
Dim somecounter As Long
Do
somecounter = somecounter + 1
If somecounter Mod 100 = 0 Then
DoEvents ' allow other tasks
End If
.......
If bDone Then Exit Do
Loop
End Function
2. In the loop in Process1() add enough DoEvents lines (e.g. 10 DoEvents per second).
For 1 you'll need a timer. To prevent reentering Process1() or to signal task has finished, you'll need a flag (Boolean variable).
' in Form_Load
ReadSomething ...
Timer1.Enabled = True ' this will start Process1
DoSomething ...
Show
Refresh
' in Timer1_Timer
Timer1.Enabled = False
If bExecuting Then Exit Sub
bExecuting = True ' set flag, defined in a module or form
Call Process1()
bExecuting = False ' reset flag
' in Process1
Public Function Process1(arg1 as String)
Dim somecounter As Long
Do
somecounter = somecounter + 1
If somecounter Mod 100 = 0 Then
DoEvents ' allow other tasks
End If
.......
If bDone Then Exit Do
Loop
End Function
Experts here very much appreciate comments when they have helped you and the results are less than "A" level results. We all take pride in delivering excellence and appreciate feedback from you anytime we fall short of those expectations so that the "missing" elements or added insights can be added. Why did you choose to grade less than an "A" here, please?
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Moondancer - EE Moderator
To add a little more explanation on grading: The goal on grading is to assess the value given in the question, and to give it the level of quality that will entice others to visit the solution if it served you once the question has migrated to our PAQ. People are more likely to visit a question in our PAQ that is an A question grade rather than one which is a lower grade. In addition, the points you give a question remain the same, but the points which flow to the expert are a direct result of the grade assigned. Example: 100 points at an A grade = 400, B = 300, C=200
Listening further. If no response will assume the grade was chosen in error and will correct.
Moondancer - EE Moderator
Visual Basic allows you to launch components in background threads when using ActiveX EXE servers, however it does not allow this when using ActiveX DLL's or regular exe. Some programmers have attempted to use the CreateThread API to perform background thread operations with VB, but the results range from unsatisfactory to disastrous (refer to our article "A Thread to Visual Basic" for details).
The dwBackThread component makes it easy for the first time to launch objects in background threads in your ActiveX DLL components which support background (asynchronous) operations.
The dwBackThread component follows all of the COM threading rules necessary to make an object work reliably with Visual Basic. It performs cleanup tasks to allow your background thread to terminate correctly even if you don't release all of your objects properly.
The Desaware background thread component is included with SpyWorks Professional 6.2 and later and the NT Service Toolkit 1.0 and later.
http://www.desaware.com/BackThreadL3.htm
Based on review and feedback from other moderators, the grade is changed.
Please see below.
Computer101
E-E Moderator
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Computer101
E-E Moderator
How Do I Know What Grade to Give?
Although we use an A-D scale here at Experts Exchange, it works differently than, say, school grades. If one or more Experts' proposals are accepted as answers, they should usually be given an A or B grade, since they have taken the time to provide you with a working solution. If a possible solution is incomplete - ask for clarification or details before accepting the answer and grading it. People should not be given lower grades because of incorrect grammar or because you just accepted their answer or comment to close the question. Keep in mind, your question and any follow-up comments should be focused so that there can be a specific answer. The following is a good guideline to follow when grading:
A: The Expert(s) either provided you with a thorough answer or they provided you with a link to information that thoroughly answered your question. An "A" can also be given to any answer that you found informative or enlightening beyond the direct question that you asked.
B: The Expert(s) provided an acceptable solution, or a link to an acceptable solution, that you were able to use, although you may have needed a bit more information to complete the task.
C: Because Experts' reliability are often judged by their grading records, many Experts would like the opportunity to clarify if you have questions about their solutions. If you have given the Expert(s) ample time to respond to your clarification posts and you have responded to each of their posts providing requested information; or if the answers, after clarification, lack finality or do not completely address the issue presented, then a "C" grade is an option. You also have the option here of just asking Community Support to delete the question.
Remember, the Expert helping you today is probably going to be helping you next time you post a question. Give them a fair chance to earn an 'Excellent!' grade and they'll provide you with some amazing support.
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