[VB6] - Module for working with multithreading.

[hennyere]

It's the bad practice to use TerminateThread because there is no resource releasing in this case. It's better to notify a thread (for example PostMessage/PostThreadMessage in certain cases) you want to finish it. If your thread is in waiting state you can use alertable state and notify by posting an APC request.

Hi The Trick,

I'm glad to see you here while I'm having a coffee.

Thanks for letting me know about using TerminateThread.

I'm trying to adapt your module into a project, and I would like to ask a question:

In a very simple approach, we have some sql statements that need to be executed asynchronously. Please keep in mind that this is a summary code, therefore the RunSqlAssync function is called in several places in the project.

Form1.frm

Private Sub Form_Load()
    modMultiThreading.Initialize
    modMultiThreading.EnablePrivateMarshaling True
End Sub

Private Sub Form_Unload(Cancel As Integer)
    modMultiThreading.Uninitialize
End Sub

Private Sub Command1_Click()
    RunSqlAssync "UPDATE mytable SET myfield1=100 WHERE myfield1=1000;"
    RunSqlAssync "UPDATE mytable SET myfield1=200 WHERE myfield1=2000;"
End Sub

Module1.bas

Public Sub RunSqlAssync(ByVal xSql As String) 
    Dim zTObj As Object, zTAsynchID As Long
    Set zTObj = modMultiThreading.CreatePrivateObjectByNameInNewThread("VBThreadClass", , zTAsynchID)
    modMultiThreading.AsynchDispMethodCall zTAsynchID, "RunSqlEx", VbMethod, Nothing, "", xSql
End Function

VBThreadClass.cls

Public Sub RunSqlEx(ByVal xSql As String)
    Dim xCmd As Object
    Set xCmd = CreateObject("ADODB.Command")
    xCmd.ActiveConnection = Db
    xCmd.CommandType = adCmdText
    xCmd.CommandText = xSql
    xCmd.Execute , , adExecuteNoRecords
    Set xCmd = Nothing
End Sub

As you noticed, every time I call RunSqlAssync, this Sub asynchronously executes RunSqlEx. This seems to work fine, but I have 2 questions:

1. What happens to the Thread when RunSqlEx reaches the end? Is it simply finished?
2. How many Threads can be executed in parallel?

I've been working with C# for years and don't have much experience with Vb6.