On Thu, Aug 09, 2018 at 02:08:56PM -0700, Junio C Hamano wrote: > > Correct. But I am more worried about the "mixed/overwriting" > > breakage, if there is one; it means we may need to be prepared for > > systems that lack O_APPEND that works correctly. I initially just > > assumed that it was what Dscho was seeing, but after re-reading his > > message, I am not sure anymore. > > > > I think the "do not trace the other side" approach you suggest for > > these tests that only care about one side is more appropriate > > solution for this particular case. We then do not have to worry > > about overwriting or output from both sides mixed randomly. > > A concluding sentence I forgot to add, after saying "this is simpler > and better to fix test breakage", was > > But if we really are seeing O_APPEND breakage, a mandatory > locking mechanism like this one might be necessary to work > around it (I seriously hope we do not have to, though). > > Sorry for an additional noise. Yeah, my earlier email said "if we just care about this test, then...". But if we do care about making this multiple-tracing case work all the time, then we'd need some solution. If there's something that can work like O_APPEND, even if we have to make some system-specific call, I'd prefer that to locking. I did some searching for atomic append on Windows and got mixed reports on whether their FILE_DATA_APPEND does what we want or not. Knowing nothing about msys, I'd _assume_ that O_APPEND would get translated to that flag, but I got lost trying to find it in git-for-windows/msys2-runtime. Wouldn't it be wonderful if the solution were as simple as making sure that flag was plumbed through? I seriously doubt it will be that easy, though. :) -Peff
