[PyKDE] timer expiration routine execution?

A.T. Hofkamp a.t.hofkamp at tue.nl
Thu Feb 13 10:15:00 GMT 2003

Hello all,

In ym animation program, I have a timer that expires for every frame
(currently about 5 times/second). The time expiration handler routine then
moves the moving objects one frame.

Which objects are to be moved is stored in a list.

At the same time, data is read from stdin (in bursts). This input causes
'old' objects to be removed from the list, and 'new' objects to be added to
the list.

Obviously, the list is a shared resource here, i.e. it is accessed both
from the input routine and from the timer expiration routine.
I currently deal with this problem by stopping the timer (QTimer.stop()),
reading and processing input, and restarting the timer.
I am wondering whether this is sufficient. In particular, could it happen
that at the moment I am calling QTimer.stop(), the timeout-handler routine
is running?
What happens then with the execution of the handler?

The PyQt book doesn't say anything about this, the QT documentation states
that "the timer stops" (I interpret this as "no new timeouts will occur
after the call returns") but nothing about the execution of the handler or
the processing of timeout-signals 'on their way' (i.e. nano-seconds before
QTimer.stop() deactivates the timer, it expires, it posts a time-out signal,
stops the timer, and returns to the read-routine).

Is there anyone that can give me an idea on how to eliminate such potential

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