[cfe-dev] Unusually high ram usage on tests

[Fāng-ruì Sòng via cfe-dev]

On Wed, Mar 10, 2021 at 10:09 PM David Blaikie via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> sometimes referred to as shared library build in the cmake config, I think
>
> Speeds up building, but slows down test execution, unfortunately - which
> balance works best for you may vary/be different from what works best for
> other folks.
>
>
> On Wed, Mar 10, 2021 at 9:41 PM Deep Majumder via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
>> Btw, how does one enable dynamic linking? I couldn't find such an option
>> in CMakeCache.txt.
>>
>> On Thu, Mar 11, 2021 at 11:09 AM Deep Majumder <
>> deep.majumder2019 at gmail.com> wrote:
>>
>>> Yup, right you are! I had reinstalled my system and forgotten to install
>>> lld. Thanks!
>>>
>>> On Thu, Mar 11, 2021 at 12:59 AM Benics Balázs <benicsbalazs at gmail.com>
>>> wrote:
>>>
>>>> Use `lld` as a linker, it is superior to `ld` or `gold`.
>>>> It consumes less memory and much faster.
>>>> Also, prefer dynamic linking for faster development cycles.
>>>>
>>>> Balazs.
>>>>
>>>>
>>>>
>>>>
>>>> ------------------------------
>>>> *From:* cfe-dev <cfe-dev-bounces at lists.llvm.org> on behalf of Deep
>>>> Majumder via cfe-dev <cfe-dev at lists.llvm.org>
>>>> *Sent:* Wednesday, March 10, 2021 8:17:38 PM
>>>> *To:* cfe-dev <cfe-dev at lists.llvm.org>
>>>> *Subject:* [cfe-dev] Unusually high ram usage on tests
>>>>
>>>> Hi everyone,
>>>> I am running 'ninja check-clang-analysis' on the release build of clang
>>>> with LLVM_PARALLEL_LINK_JOBS set to 2 and assertions off. I am on Ubuntu
>>>> 20.04. This is taking up almost 10 gb of memory (6 from ram, 4 from swap).
>>>> I have been running this command for over a month and I haven't seen this
>>>> sort of memory usage. Is this normal? Or am I missing something?
>>>> Warm regards,
>>>> Deep
>>>>
>>> _______________________________________________
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-DBUILD_SHARED_LIBS=on

The increase on test execution time is huge so I only use it for
-DCMAKE_BUILD_TYPE=Debug where I only tend to run a small set of tests
during development.

Having both -DBUILD_SHARED_LIBS=on & -DBUILD_SHARED_LIBS=off configurations
is handy when you add #include:
-DBUILD_SHARED_LIBS=on on Linux enables -Wl,-z,defs which requires every
shared object to have full direct dependencies specified (gold and ld.lld
behavior; not in GNU ld),
basically "link what you use" (similar to "include what you use").
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