On 1/3/2016 1:18 PM, "Torsten Hüter" wrote: > Hi Wayne, > > I've recently tried to compile KiCad on Windows (64Bit) and I've noticed that > PcbNew is crashing at context switching - but I had no problems early 2015 > with that. I've seen that you have already filed a bug report [1]. I did some > research and this thing seems to cause constantly trouble, because some > assembly "hackery" is required and only MASM is officially supported [2]. > > Rather than trying to fix Boost, makes it sense to consider an alternative > way or library for the same purpose? > > I've found so far these alternatives as back-end for "stackful" coroutines: > > (1) Fibers on Windows > > https://msdn.microsoft.com/de-de/library/windows/desktop/ms682661%28v=vs.85%29.aspx > https://en.wikipedia.org/wiki/Fiber_%28computer_science%29
What version(s) of Windows support fibers? I didn't see any indication on the links above. > > This seems to be the safest alternative for Windows, because Fibers are fully > supported by the OS and are thread-safe. > > (2) POSIX ucontext.h - setcontext, getcontext, makecontext and swapcontext > > Very similar compared to Windows Fibers, but deprecated since POSIX.1-2008, > quote from https://en.wikipedia.org/wiki/Setcontext : > > "[..] POSIX.1-2004 obsoleted these functions, and in POSIX.1-2008 they were > removed [..]" > > It is still possible to use these functions on Linux, but these are not > future-proof and there are no replacement functions. > > An interesting talk about this topic can be found here: > http://stackoverflow.com/questions/4298986/is-there-something-to-replace-the-ucontext-h-functions > > (3) POSIX Threads > > https://computing.llnl.gov/tutorials/pthreads/ > > It is possible to emulate Fibers with pthreads, here is a good article about > this subject: > > http://sjansen.blogspot.de/2008/04/coroutines-in-cc-beyond-duffs-device.html > > The downside is the larger overhead, but this shouldn't be a big issue for > KiCad, I'm sure that not more than a few coroutines are created for the tool > framework. Quote from the above article: > > "[..] As an interesting sidenote, I'm not sure how debuggers such as gdb and > valgrind handle applications that switch their stacks. It might be that using > threads actually makes things easier to debug in this case (as the tools > already have support for threads). [..]" > > Pthreads offer also some mechanisms for stack overflow detection. > > (4) setjmp / longjmp > > https://en.wikipedia.org/wiki/Setjmp.h > > Context switching is also possible using these functions and some libraries > like "picoro" use that for Coroutines. However stack handling is difficult, > especially stack overflow protection is not easy to implement. > > http://dotat.at/cgi/git/picoro.git > > -- > > Summary: Fibers (Windows) and Pthreads (all POSIX-compliant operating > systems) seem to be the most promising alternatives for context switching. > This way it would be possible to get rid of the Boost.Context dependency > while using standard libraries. > > What do you think, should I invest more time into this topic (refactoring of > coroutine.h using these alternatives and write a stress test application)? I don't have any strong opinions either way. However, I did not write the code. Tom may have a stronger opinion about this than I do since he wrote the code. Personally I'm not the biggest fan of coroutines. I know the make the code easier to read but I'm not convinced they are necessary in an event driven design. Thanks for the links. They are interesting. Cheers, Wayne > > Thanks, > Torsten > > [1] KiCad issues with Boost 1.59, bug report, > https://github.com/Alexpux/MINGW-packages/issues/836 > [2] Boost context requirements, > http://www.boost.org/doc/libs/1_60_0/libs/context/doc/html/context/requirements.html > > _______________________________________________ > Mailing list: https://launchpad.net/~kicad-developers > Post to : [email protected] > Unsubscribe : https://launchpad.net/~kicad-developers > More help : https://help.launchpad.net/ListHelp > _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
