Very high CPU usage with QTableView and MVC

[wysota]

Could you set break points in your code using a debugger and check where exactly does you application spin all the time? Alternatively run your application under a profiler (such as callgrind or gprof) and see what takes the most time.

[montylee]

Could you set break points in your code using a debugger and check where exactly does you application spin all the time? Alternatively run your application under a profiler (such as callgrind or gprof) and see what takes the most time.

ok let me see if i can do that. I haven't used a profiling tool yet so let me see.
By the way, even if i hide my application, CPU usage is high, so it's not because of drawing etc...

very strange and weird issue...

[aamer4yu]

Check the data function. May be you are consuming time to fetch data...

EDIT: Oops... u are using standardItemModel...so data fetching is also not in your hands...
prob must be somewhere else.. check for events and how you are handling them..

[montylee]

ya i guess the problem is somewhere else as the problem is coming with QStandardItemModel as well. I haven't got time to debug this issue yet, have been busy in other things. Will update this thread when i am able to debug this issue.

[montylee]

Could you set break points in your code using a debugger and check where exactly does you application spin all the time? Alternatively run your application under a profiler (such as callgrind or gprof) and see what takes the most time.

Aah, i found the cause of the problem. I compiled the program with -pg option and used gprof to check which API was taking all the CPU time.

I found that it was QAbstractItemView::timerEvent(QTimerEvent * event). I wanted the contents of the table rows to scroll so i implemented a timer by subclassing QAbstractItemView::timerEvent(QTimerEvent * event) in my class. But due to this, the CPU usage goes high.

I think i'll use a normal QTimer instead of reimplementing QAbstractItemView::timerEvent(QTimerEvent * event).

Don't know why QAbstractItemView::timerEvent(QTimerEvent * event) is causing this problem though.

[wysota]

I don't think using QTimer will help, it's heavier than a timer event. I'd say you should control the interval properly and stop the timer once you reach your goal although I have no idea what you are doing.

[montylee]

actually the timer needs to be active as long as the widget is showing because the contents of the table row needs to be scrolled. I can stop the timer when the widget gets hidden.
But still using a timer shouldn't cause the CPU usage to be so high.