[Interest] QTimer stops triggering

Tue Jun 5 13:04:29 CEST 2012

André:

> > I don't know what timer API is used by Qt. If it's Posix timers underneath,
> > can you try a simple app with Posix timers and see if they also misbehave.
> > That way, we will know whether it's a platform problem or qt problem.

> Seems to me that no matter what technology Qt uses under the hood, it is
> always a Qt problem. Qt does not advertise any limitations on this front,
> so it should not suffer any. If the platform does not support the functionality
> directly, it is up to Qt to work around that IMHO.

  Absolutely true.

  But still, it would be valuable to know whether one needs to design a
  work-around to a platform problem or just fix a Qt bug.

                                Atlant

From: interest-bounces+aschmidt=dekaresearch.com at qt-project.org [mailto:interest-bounces+aschmidt=dekaresearch.com at qt-project.org] On Behalf Of André Somers
Sent: Monday, June 04, 2012 10:26
To: interest at qt-project.org
Subject: Re: [Interest] QTimer stops triggering

Op 4-6-2012 16:19, Pritam schreef:
On Monday 04 June 2012 07:36 PM, Vannoote, Frederik wrote:
Hi Syam,

The Qtimer object is only created once and lives on for ever.
It has an interval of 30 seconds.

Most of the times they stop triggering after 1 or 2 days.

I dont know what timer API is used by Qt. If its posix timers underneath, Can you try a simple app with posix timers and see if they also misbehave.
That way, we will know whether its a platform problem or qt problem.
Seems to me that no matter what technology Qt uses under the hood, it is always a Qt problem. Qt does not advertise any limitations on this front, so it should not suffer any. If the platform does not support the functionality directly, it is up to Qt to work around that IMHO.

André

Kind regards,
Frederik

Frederik Vannoote

Sr. Development Engineer Software

Barco nv

Pres.Kennedypark 35

B-8500 Kortrijk (Belgium)

________________________________
From: interest-bounces+frederik.vannoote=barco.com at qt-project.org<mailto:interest-bounces+frederik.vannoote=barco.com at qt-project.org> [mailto:interest-bounces+frederik.vannoote=barco.com at qt-project.org] On Behalf Of Syam Krishnan
Sent: 04jun12 16:04
To: interest at qt-project.org<mailto:interest at qt-project.org>
Subject: Re: [Interest] QTimer stops triggering

On 06/04/2012 12:34 PM, Vannoote, Frederik wrote:
Hey all,

I'm having a weird thing about Qtimer which I can't explain until now.
We are using a dedicated application to kick the processor watchdog. This application is based on a QTimer. Basically, it only has to call an ioctl once every 30 seconds. This is the only thing the application does.

We see that after a random time, the QTimer stops triggering. We have proven that it does not get stuck somewhere, it just does not get scheduled any more.
I've replaced the code with a while loop instead of the QT event loop. That seems to be running fine.

Do you mean to say that you have set the QTimer to have a time-out of 30 seconds?
And what is the order of time after which the timer seems to stop working - minutes, hours?

Also, (a wild shot) are you by any chance creating the timer objects afresh everytime?

Syam

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