[Development] [fix]: Assistant (and others) burning CPU because of #f27d1ccbb24ec2fd4098f2976503478831006cc8 ?

[Philippe]

Maybe even deprecate startTimer and killTimer?

-1

I like this low level insight, which gives me a higher sense of control about what's going on.

Philippe

On Wed, 30 Aug 2017 08:06:35 +0000
Lars Knoll <lars.knoll at qt.io> wrote:


>> On 30 Aug 2017, at 09:30, Olivier Goffart <olivier at woboq.com> wrote:
>> 
>> Am Dienstag, 29. August 2017, 17:30:56 CEST schrieb Thiago Macieira:
>> On Tuesday, 29 August 2017 01:10:53 PDT René J.V. Bertin wrote:
>>> Which we just rediscovered :) Funny though, apparently 1 misdirected
>>>> startTimer() call can turn any application in a CPU hog that burns cycles
>>>> without ever doing anything. Wouldn't it be safer for
>>>> QObject::timerEvent()
>>>> to kill any timer that triggers it, possibly even do an abort if it can do
>>>> some kind of runtime debug mode detection? At least then it's set to a 0
>>>> (zero) interval?

Sure. Please tell that to Eirik and Håvard back in the early 90s when
they're designing Qt.
http://doc.qt.io/archives/2.3/qobject.html#4c6b67
(Qt 1 docs not online)

Unfortunately, we can't change anymore.

We can change the documentation and recommend against using killTimer and 
startTimer. QBasicTimer should be used instead. This would have probably 
avoided the problem in this case (as one would have called stop instead of 
m_updateTimer = 0). And in general is easier to use for 0 overhead.



+1. Maybe even deprecate startTimer and killTimer?


Cheers,
Lars



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