Liviu Nicoara updated STDCXX-1056:

    Attachment: STDCXX-1056-additional-timings.tgz
> std::moneypunct and std::numpunct implementations are not thread-safe
> ---------------------------------------------------------------------
>                 Key: STDCXX-1056
>                 URL: https://issues.apache.org/jira/browse/STDCXX-1056
>             Project: C++ Standard Library
>          Issue Type: Bug
>          Components: 22. Localization
>    Affects Versions: 4.2.1, 4.2.x, 4.3.x, 5.0.0
>         Environment: Solaris 10 and 11, RedHat and OpenSuSE Linux, Sun C++ 
> Compilers 12.1, 12.2, 12.3
> Issue is independent of platform and/or compiler.
>            Reporter: Stefan Teleman
>              Labels: thread-safety
>             Fix For: 4.2.x, 4.3.x, 5.0.0
>         Attachments: 22.locale.numpunct.mt.out, runtests-linux32-all.out, 
> runtests-linux64-all.out, runtests.out, STDCXX-1056-additional-timings.tgz, 
> stdcxx-1056.patch, stdcxx-1056-timings.tgz
> several member functions in std::moneypunct<> and std::numpunct<> return
> a std::string by value (as required by the Standard). The implication of 
> return-by-value
> being that the caller "owns" the returned object.
> In the stdcxx implementation, the std::basic_string copy constructor uses a 
> shared
> underlying buffer implementation. This shared buffer creates the first 
> problem for
> these classes: although the std::string object returned by value *appears* to 
> be owned
> by the caller, it is, in fact, not.
> In a mult-threaded environment, this underlying shared buffer can be 
> subsequently modified by a different thread than the one who made the initial 
> call. Furthermore, two or more different threads can access the same shared 
> buffer at the same time, and modify it, resulting in undefined run-time 
> behavior.
> The cure for this defect has two parts:
> 1. the member functions in question must truly return a copy by avoiding a 
> call to the copy constructor, and using a constructor which creates a deep 
> copy of the std::string.
> 2. access to these member functions must be serialized, in order to guarantee 
> atomicity
> of the creation of the std::string being returned by value.
> Patch for 4.2.1 to follow.

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