Am 06.09.2017 16:48 schrieb "el es via Lazarus" < lazarus@lists.lazarus-ide.org>: > > On 06/09/17 15:26, el es wrote: > > On 06/09/17 10:31, Andrea Mauri via Lazarus wrote: > >> Il 05/09/2017 22:51, Sven Barth via Lazarus ha scritto: > >>> > >>> It is however solved if you add a "Yield;" after the Synchronize > >>> call. So my suspicion is that the scheduling of Mac OS X is somehow > >>> messing things up. Either the scheduling is favoring the one thread > >>> while it shouldn't (though even reducing the priority doesn't help) > >>> or the UI framework of Mac OS X (and whatever else is involved in > >>> the main thread) is so heavy weight that the timeslice of the > >>> mainthread is used up more often than not thus leading to the read > >>> thread being scheduled much more often. By using Yield (or also > >>> Sleep(), but Yield is without any pause) the thread is explicitly > >>> giving up its timeslice and that seems to be enough here... > >>> > >> > >> I changed the code following your hints and I added Yield. This is > >> not enough, it seems that the application is a little bit more > >> responding (I can click on Tedit and after seconds the text is > >> highlighted) but not enough to be usable. Actually for me it works > >> only if I add at least Sleep(1). It is a pity that there is not a > >> unique solution. > > > > Can you try ThreadSwitch after Sleep ? > > > > while (not Terminated) do > > begin > > if eof(f) then > > reset(f); > > ReadLn(f, newStatus); > > if NewStatus <> fStatusText then > > begin > > fStatusText := newStatus; > > //Queue(@ShowStatus); > > Synchronize(@Showstatus); > > Sleep(5); > > ThreadSwitch; /// <<<< > > end > > else // also you need to cover what happens in ANY OTHER outcome of any test, e.g. > > ThreadSwitch; > > // because if NewStatus = fStatusText, you will IMMEDIATELY jump to the first instruction of the thread > > // so adding the ThreadSwitch at the very end of the loop, you give the rest of the application (the main thread) a chance to > > // actually do anything > > end; > > > > Thread.Execute will execute ALL THE TIME if you don't yield/threadswitch in some code path, and WILL saturate your CPU. > > > > -l, > > > > In addition to why this isn't a problem on Windows or Linux: they have supposedly better schedulers... > > but if not all codepaths on a thread are covered to give some time to main thread, try to imagine what happens: > > - could the un-yielded code path lead to over-zealous enqueuing of the ShowStatus routine? > - if yes, what would happen in such case?
Both Synchronize and Sleep already causes a thread switch (the former cause it will wait for the main thread to finish processing). Also I already suggested TThread.Yield which is the same as ThreadSwitch. And as he wrote the Sleep(1) solves the problem for him. It's a pity though that this seems to be necessary on Mac OS X :/ Regards, Sven
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