[Qt-interest] Qthread takes a long time to stop

[Scott Bloom]

You basiclly answered it yourself.

You need to shorten the getmessage and processMessage functions...

One very common technique, is inside the algorithms, query if they are
allowedToRun();

Ie..

HelperThread::getmessage()
{
    if( !allowedToRun() ) return;
   step1();
    if( !allowedToRun() ) return;
    step2();
    if( !allowedToRun() ) return;
   step3();
}

And the same for processMessage()..

But at some point you will get down to a 3rd party library call, which you
cant make any smaller... That will be the minimum wait time :(

Scott


On 6/19/10 8:02 AM, "Sarvesh Saran" <Sarvesh.Saran at synopsys.com> wrote:

> Hi,
>  
> I have a helper thread derived from QThread which runs in a forever loop.
> Inside the loop it reads messages from a server , does some processing of the
> messages and send the message to the Main GUI thread.
>  
> So the helper thread looks something like:
>  
> Helperthread::run()
> {
>                 while(allowedToRun())
>                 {
>                                 QString msg;
> getmessage(&msg); //read a message from the server
> processMessage(msg);
>                 }
> }
>  
> Helperthread::processMessage()
> {
> //lots of case statements hereŠ.(to identify message types) and lots of
> message processing
> }
>  
> //this is a public slot called by the main GUI thread
> Helperthread::setAllowedToRun()
> {
> //set the flag to false;
> }
>  
> My problem is that when the main window gets a close signal, it sets the flag
> to false and has to wait for a long time for the helper thread to finish.
>  
> i.e in the main window on close :
>  
> MainWindow::closeEvent()
> {
> helperthread->setAllowedToRun(false);
> helperthread->wait();  //this takes a long time because the helper thread¹s
> processMessage is quiet big and takes a long while to return.
> }
>  
> Is there a way I can speed this up so that my main window does not have to
> wait for a long time for the helper thread to exit ?
>  
>  
> Thanks,
> Sarvesh
> 
> 
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