Re: Reduce libstdc++-v3 locale::locale() lock contention

[Jimmy Guo <jguo at yahoo-inc dot com>]

>> Actually I was digesting your response and had just finished another patch
>> (need to build and test) in this area.  The 8 threads case in my test
>> results shows multi-core scalability issue and it may have to do with cache
>> line ping-pong.  Here is the preliminary patch (against an old gcc tree ...
>> will clean it up for gcc trunk next), see if I'm on the right path or not:
>>   
> Definitely you are, about the issue of principle! Now however, while
> doing this work, consider the ABI in the generalized sense which we care
> about: I see you are touching a .h header and that scares me: what
> happens if people try to link together two objects built with old and
> new locale_classes.h, and a classic locale is passed around? Please
> always give this sort of issue a lot of thought when proposing patches
> for the library (until we decide to officially break the ABI of course)

Yes you are right.  Cannot do this without ABI breakage.  The old object
handling destruction will cause problem.

- Jimmy