[llvm-dev] [RFC] Free memory allocated for ManagedStaticMutex

[Justin Holewinski via llvm-dev]

How does keeping the DLL in-memory help with not leaking the mutex? Or is
the recommendation to just ignore the leak?

On Fri, Oct 26, 2018 at 9:32 AM Sotkin, Alexey via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi Reid,
>
>
>
> Thanks for the feedback. Could you elaborate on pinning and dropping
> topic. I don’t quite understand what do you mean.
>
>
>
> Thanks,
>
> Alexey Sotkin
>
> *From:* Reid Kleckner [mailto:rnk at google.com]
> *Sent:* Monday, October 22, 2018 11:57 PM
> *To:* Sotkin, Alexey <alexey.sotkin at intel.com>
> *Cc:* llvm-dev <llvm-dev at lists.llvm.org>; Maksimova, Viktoria <
> viktoria.maksimova at intel.com>
> *Subject:* Re: [llvm-dev] [RFC] Free memory allocated for
> ManagedStaticMutex
>
>
>
> Let's not do this. It's really best for global mutexes to live for the
> entire process lifetime. Initializing them and deinitializing them just
> asks for races. Perhaps you can avoid this problem by pinning your LLVM DLL
> in memory by LoadLibrary'ing it and dropping the reference.
>
>
>
> On Mon, Oct 15, 2018 at 3:54 AM Sotkin, Alexey via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> Hi,
>
>
>
> In llvm_shutdown function we destroy all objects in the StaticList. This
> procedure as well as RegisterManagedStatic are guarded by
> ManagedStaticMutex which is a static pointer visible only in
> ManagedStatic.cpp. Memory for the mutex is allocated at initializeMutex
> function and we never free this memory. From my experience this can cause a
> memory leak problem if we create a dll linked with LLVM libraries and the
> dll gets loaded(LoadLibrary Windows API) and unload(FreeLibrary Windows
> API) at runtime many times.
>
> My proposal is to provide deleteManagedStaticMutex LLVM API, so we can
> deallocate the mutex from DllMain on Windows. Please take a look at
> https://reviews.llvm.org/D52425
>
> I also think it’s worth adding deleteManagedStaticMutex to
> llvm_shutdown_obj’s destructor. I have attached valgrind logs with and
> without deleting ManagedStaticMutex.
>
>
>
> *Best regards.*
>
> *Alexey Sotkin.*
>
>
>
>
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-- 

Thanks,

Justin Holewinski
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