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https://issues.apache.org/jira/browse/STDCXX-1056?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13461253#comment-13461253
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Liviu Nicoara commented on STDCXX-1056:
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FWIW, I attached two simple patches which eliminate caching of facet data, one
binary compatible, for 4.2.x, the other for 4.3.x and later. The current locale
MT tests pass with gcc and SUNPro on Linux.
> 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,
> stdcxx-4.2.x-numpunct-perfect-forwarding.patch,
> stdcxx-4.3.x-numpunct-perfect-forwarding.patch
>
>
> 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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