On Sun, May 15, 2005 at 05:09:39PM +0300, Martin Vermeer wrote: > Lars, > > Now that I have had some time to think it over, I am more and more > inclined to suspect that there is something to my dark fear. > > As I understand it, LyX, Qt and X all process events in a "linear" > fashion. This means, that routines call subroutines (stacking their > context), calling subroutines, etc... until they return and unwind their > contexts. > > The event loop (X or Qt) is no different. > > Under such a scheme it is _in principle impossible_ for function calls > in different places in the code to pre-empt each other. The keystroke > reversal we saw just cannot come about. > > So, _something_ is happening non-linearly, through pre-emption. We know > of course that this kind of thing is happening on the system level all > the time (hardware clock interrupt etc., process/thread switching). But > this is irrelevant for our problem. It would be surprising if the same > happened inside LyX. > > However... looking at my Makefile, I see > > QT_CPPFLAGS = -DQT_CLEAN_NAMESPACE -DQT_GENUINE_STR > QT_INCLUDES = -I/usr/lib/qt-3.3/include > QT_LDFLAGS = -L/usr/lib/qt-3.3/lib > QT_LIB = -lqt-mt > QT_VERSION = 3.3.3 > > qt-mt, doesn't that mean Qt multi-threading? Or am I holding the wrong > end of the stick?
Yes, it means multithreading. However, I wouldn't suspect it of magially starting to multithread an application. I always thought that qt-mt merely supported multithreading - i.e. qt-mt won't mysteriously break *if* your program is multithreaded, but qt(non-mt) may show some very strange errors with a multithreaded program. I don't know qt very well, but this is how mt- and non-mt versions of other libraries tend to work. An mt-version is multithread-safe, while the non-mt version is either older or uses some optimizations that won't work in a multithreaded environment. An mt-version will be thread-safe in that everything either is reentrant code, or use some sort of semaphore to protect anything that isn't automatically thread-safe. Helge Hafting
