A consequence of using `__thread` on Apple is that initializers for thread locals are required to be constant expressions. This is not the case for the c++11 standard `thread_local`.
Can you expand on the benefits of 'thread_local'? Is the above statement alluding to tech debt or preventing new features or performance? @vinodkone > On Dec 20, 2016, at 7:04 PM, Michael Park <mp...@apache.org> wrote: > > Joris, I don't have a strong stance here. I was just providing a data point > of what people may experience out of the box. > > Am I correct in understanding the following implications? > - 10.10 would require brew-installed clang to work > - 10.11 would require a Xcode upgrade > - 10.12 would work out of the box > >> On Mon, Dec 19, 2016 at 6:27 PM, James Peach <jor...@gmail.com> wrote: >> >> >>> On Dec 19, 2016, at 3:00 PM, Joris Van Remoortere <jo...@mesosphere.io> >> wrote: >>> >>> Thanks for your input Zameer. >>> >>> Is it common for developers on mac to use XCode as their compilation >>> environment as well? I would think if you used clang on the command line >>> then you could still install an updated version of clang without having >> to >>> do a system upgrade from Yosemite? >> >> Xcode provides both the integrated development environment (typically not >> used with Mesos) and one or more toolchains and SDKs (used by Mesos). >> Whether the modern toolchain can be used with an older release depends on >> whether the Xcode release is considered supported on that release. >> >>> >>> I'm getting the impression that it's reasonable to make this change >> without >>> a deprecation cycle. Please let me know if you (anyone) disagrees. >>> >>> — >>> *Joris Van Remoortere* >>> Mesosphere >>> >>>> On Mon, Dec 19, 2016 at 2:17 PM, Zameer Manji <zma...@apache.org> wrote: >>>> >>>> I believe this thread_local support is in XCode 8.2. From the link you >>>> shared: >>>> >>>>> Xcode 8.2 requires a Mac running macOS 10.11.5 or later >>>> >>>> This means that users can upgrade the compiler on El Capitan just fine >>>> without a system upgrade. >>>> >>>> Users on Yosemite need to do a system upgrade to pick up the new >> compiler >>>> however. >>>> >>>> On Mon, Dec 19, 2016 at 12:33 PM, Joris Van Remoortere < >>>> jo...@mesosphere.io> >>>> wrote: >>>> >>>>> Is my understanding incorrect regarding the ability to upgrade the >>>> compiler >>>>> version on Yosemite and El Capitan without requiring a full system >>>> upgrade? >>>>> >>>>> @Mpark are you making a case for not updating to `thread_local` just >> yet? >>>>> >>>>> — >>>>> *Joris Van Remoortere* >>>>> Mesosphere >>>>> >>>>> On Fri, Dec 16, 2016 at 11:11 AM, Michael Park <mp...@apache.org> >> wrote: >>>>> >>>>>> Brief survey from the #dev channel: https://mesos.slack.com/ >>>>>> archives/dev/p1481760285000430 >>>>>> >>>>>> Yosemite 10.10: Fail. Compilation error. (by @hausdorff >>>>>> https://mesos.slack.com/archives/dev/p1481760552000435) >>>>>> El Capitan 10.11: Fail. Compilation error. (by @zhitao >>>>>> https://mesos.slack.com/files/zhitao/F3F7WUCNM/-.diff) >>>>>> Sierra 10.12: Success (by @mpark) >>>>>> >>>>>> On Wed, Dec 14, 2016 at 3:27 PM, Joris Van Remoortere < >>>>> jo...@mesosphere.io >>>>>>> >>>>>> wrote: >>>>>> >>>>>>> The time has come and we finally have `thread_local` support in the >>>>> Apple >>>>>>> tool chain: >>>>>>> https://developer.apple.com/library/content/releasenotes/Dev >>>>>>> eloperTools/RN-Xcode/Introduction.html >>>>>>> >>>>>>> In our code base we have a special exception for Apple that defines >>>> our >>>>>>> thread local to be `__thread` rather than the c++11 standard >>>>>>> `thread_local`. >>>>>>> https://github.com/apache/mesos/blob/812e5e3d4e4d9e044a1cfe6 >>>>>>> cc7eaab10efb499b6/3rdparty/stout/include/stout/thread_local.hpp >>>>>>> >>>>>>> A consequence of using `__thread` on Apple is that initializers for >>>>>> thread >>>>>>> locals are required to be constant expressions. This is not the case >>>>> for >>>>>>> the c++11 standard `thread_local`. >>>>>>> >>>>>>> I would like to propose that we remove this exception on the Apple >>>>>> platform >>>>>>> now that the Apple toolchain supports the c++11 standard. >>>>>>> >>>>>>> As I am not a common user of the Apple development experience I would >>>>>> like >>>>>>> to ask for some input from the community as to whether requiring this >>>>>>> toolchain update is acceptable, and if we need a deprecation period >>>> or >>>>> if >>>>>>> we can just make this change now. >>>>>>> >>>>>>> I am leaning towards no deprecation period as I am not aware of >>>>>> production >>>>>>> environments running on systems that define `__APPLE__`. >>>>>>> — >>>>>>> *Joris Van Remoortere* >>>>>>> Mesosphere >>>>>>> >>>>>> >>>>> >>>>> -- >>>>> Zameer Manji >>>>> >>>> >> >>
