> Can anyone please tell me what is wrong with this code? When
> I debug it, it sometimes generate error at the line v[i] =
> i; in RunProcesses().
Not for me - what tools are you using? How are you testing this?
For me it fails at this line in plot_cb();
output_2->value(msg);
The reason why is pretty obvious; you have never initialised output_2
widget.
(The output_2 widget is declared but never initialised in your code.)
You probably meant output_3 widget, and if I make that change it seems
to work OK.
Further comments below:
> volatile int v[100000];
This array declared volatile as it is shared between threads.
> void plot_cb(void *p)
> {
> char msg[256];
>
> int *data = (int*)p;
> sprintf(msg, "%d", *data);
>
> Fl::lock();
> // Obtain a lock before we access the browser widget...
NEVER call lock from this CB - it is executed in the main thread, not a
worker thread, so the lock will be managed by fltk.
This is described in the docs, so I am surprised that you have done
this...
>
> output_2->value(msg);
> output_2->redraw();
Widget output_2 is never initialised - you mean output_3 I think.
> Fl::unlock();
> // Release the lock...
>
> Fl::awake();
NEVER call unlock() or awake() from this CB, it is in the main thread.
See note above.
> }
> unsigned WINAPI RunProcesses(LPVOID lpParam)
> {
> int i;
>
> for (i=0; i<100000; i++)
> {
> v[i] = i;
> Fl::awake(plot_cb, (void*)&v[i]);
Calling awake() many times from the worker thread with no delay between
calls is horribly inefficient.
Do not do this, find a way to coalesce multiple updates to pass to the
GUI at a more moderate rate, say a few hundred Hz max.
> }
> return (unsigned)1;
> }
>
>
> static void start_cb(Fl_Button *b, void *p)
> {
> unsigned threadID;
> char msg[256];
>
> sprintf(msg, "%s", "");
>
> Fl::lock(); // Obtain a
> lock before we access the browser widget...
DO NOT lock here...
>
> output_3->value(msg);
> output_3->redraw();
>
> Fl::unlock(); // Release the lock...
>
> Fl::awake();
And again... These callbacks occur in the main thread, so locking is not
necessary.
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