[cfe-dev] [clangd] Worker threads stack size

[Roman Popov via cfe-dev]

In case MacOS LibC++ is implemented on top of pthreads, than you can can
use pthreads API to set default stack size. This will probably be miminal
possible platform-specific workaround.

пт, 17 авг. 2018 г. в 6:27, Ilya Biryukov via cfe-dev <
cfe-dev at lists.llvm.org>:

> Would be nice to get around this limitation in the standard library. I
> don't think we can do it in a standard-compliant way, though.
> There's `llvm::llvm_execute_on_thread`, but it is an OS-specific
> implementation.
>
> Are there any ways to set default stack sizes for the newly created
> threads? Even if it's platform-specific code, it should be pretty localized
> and we could reuse the STL implementation of threads.
> I don't know of reliable APIs to do that, unfortunately.
>
> On Fri, Aug 17, 2018 at 2:43 PM Eric Liu <ioeric at google.com> wrote:
>
>> +clangd-dev at lists.llvm.org <clangd-dev at lists.llvm.org> +Ilya Biryukov
>> <ibiryukov at google.com>
>>
>> On Fri, Aug 17, 2018 at 2:41 PM Dmitry.Kozhevnikov at jetbrains.com via
>> cfe-dev <cfe-dev at lists.llvm.org> wrote:
>>
>>> Hello!
>>>
>>> clangd uses std::thread for spawning worker threads to parse files (see
>>> AsyncTaskRunner::runAsync in tools/clang/tools/extra/clangd/Threading.cpp).
>>> Unfortunately, std::thread lacks the ability to customize the stack size,
>>> and the default one might be insufficient for parsing complex source files.
>>> For example, on macOS, the default stack size for non-main threads is 512K,
>>> so the following code causes a stack overflow (on my machine) with clangd,
>>> while being way below the default constexpr evaluation depth threshold:
>>>
>>>         constexpr int foo(int x) {
>>>             return x == 1 ? 1 : foo(x - 1) + 1;
>>>         }
>>>         static_assert(foo(50) > 0, "");
>>>
>>> This also can be observed on some real-world projects.
>>>
>>> Do I understand correctly that the only way to fix it would be to
>>> abandon std::thread and reimplement the platform-specific thread spawning
>>> (using pthreads/WinAPI), or is there another solution available in
>>> LLVM/clang codebase?
>>>
>>> Best regards,
>>> Dmitry Kozhevnikov._______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>
>>
>
> --
> Regards,
> Ilya Biryukov
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20180817/3be69083/attachment.html>