Boost.Thread 1.57 breaks Windows XP compatibility for SP2 and below.

[felixbruns@…]

The commit 04e3d918 [1] introduced a call to GetLogicalProcessorInformation [2], which is only supported on Windows XP SP3 (or x64) and above.

Is Windows XP SP2 support officially dropped or was this an unintentional break?

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(1): github.com/boostorg/thread/commit/04e3d918fbf31792b6553d6cc2002214ea671aa9

(2): msdn.microsoft.com/en-us/library/windows/desktop/ms683194%28v=vs.85%29.aspx

[viboes]

I think it would be good that physical_concurrency calls hardware_concurrency if it can not be implemented.

Tim please, could you take care of this issue?

[timblechmann]

not intentional. vicente, thinking about a good fallback, i'd actually prefer to return 0 instead of calling hardware_concurrency: the reason is simple: code that depends on distinguishing the number of physical and the number of virtual processors, can rely on this. if it returns 0, the user can call hardware_concurrency.

[viboes]

Ok, no problem.

Felix, does the following covers your expectations ​https://github.com/boostorg/thread/pull/32 ?

Thanks Tim.

[Felix Bruns <felixbruns@…>]

Thanks for the quick fix! :-)

[anonymous]

If I'm not mistaken, comments are not allowed after the backslash in mutliline macros, so the line

|| ( BOOST_USE_WINAPI_VERSION <= BOOST_WINAPI_VERSION_WINXP ) \ // a bit too strict: Windows XP with SP3 would be sufficient

will fail to compile (at least does in VS2010).

[viboes]

​https://github.com/boostorg/thread/commit/8e1be55c6d560c44fb07cc497a3480527957576c