@JonB said in QTimer handle leak from inside Qt?:

@magnus.ni
There seem to be two possibilities:

• Despite what you say, your code is somehow creating many timers (e.g. via slots). Are you freeing the QTimers when you're done with them? If you are only using QTimer::singleShot, do you need those instances, could you just use the static version?

I'm very seldom explicitly create timers on the heap and almost any of those are single members of a class and bound to the lifetime of the owning class.
I didn't find any ownership problems or recursive slot mechanisms here. When I need single shot I almost always use the static version.

• As e.g. @SGaist said in https://forum.qt.io/topic/54438/solved-qt-5-4-1-qtimer-using-up-all-handles-for-window-manager-objects, it may not be the QTimer itself which is being repeatedly created. The error message could just indicate that you are using up too many Windows handles in general, e.g. from widgets or whatever else in your code. (In that link it turned out the OP was creating multiple QNetworkAccessManagers --- not saying that's you, but could be anything.)

I've read the thread but didn't use the QNetworkAccessManager or something familiar. I've seached the large codebase for any obvious QTimer misusages but without being able to reproduce the issue. But any idea why this might have implicitly occurred are most welcome since I already watched any QTimer construction in the code for possible side effects like this.

Thank you very much

@magnus.ni

Hi and welcome to devnet forum

This is merely a user's forum. Your question is probably better suited in the developer's mailing list.

Also your Qt version is fairly old. Can't you update to more recent versions? We have already version 5.12.

Thank you very much. I'm afraid this won't be possible. Maybe we can switch to 5.6 in the nearest future (since we're stuck to msvc2010 and 5.6 is the latest build supporting it)

@dheerendra said in QTimer handle leak from inside Qt?:

If the process is running you can get the details of handles which are open. Either use process explorer or sone other tool to see the handle details. It is possible that timer error just a manifestation of some other issue.

Thank you. This might be possible. But I myself cannot reproduce the issue or have seen it live.

• Despite what you say, your code is somehow creating many timers (e.g. via slots). Are you freeing the QTimers when you're done with them? If you are only using QTimer::singleShot, do you need those instances, could you just use the static version?

• As e.g. @SGaist said in https://forum.qt.io/topic/54438/solved-qt-5-4-1-qtimer-using-up-all-handles-for-window-manager-objects, it may not be the QTimer itself which is being repeatedly created. The error message could just indicate that you are using up too many Windows handles in general, e.g. from widgets or whatever else in your code. (In that link it turned out the OP was creating multiple QNetworkAccessManagers --- not saying that's you, but could be anything.)

Hi and welcome to devnet forum

This is merely a user's forum. Your question is probably better suited in the developer's mailing list.

Also your Qt version is fairly old. Can't you update to more recent versions? We have already version 5.12.