Re: [lmi] Parallel blues

[Greg Chicares]

On 2016-07-30 20:46, Vadim Zeitlin wrote:
> On Sun, 24 Jul 2016 15:11:14 +0000 Greg Chicares <address@hidden> wrote:
[...]
> GC> This is a dead end. Threading turns out not to be a silver bullet.
> 
>  I think this is slightly unfair as it does exactly what we expected, i.e.
> achieves a slightly better speed up than using GNU parallel under Linux. It
> just doesn't compensate for the awful performance of std::regex.

I guess that (what you expected) < (what I naively hoped).

> GC> I think we should just put this back on the shelf and reconsider it
> GC> when the new standard libraries have matured.
> 
>  I'm afraid we might be waiting for quite some time. If one of the
> explanations of Boost.Regex performance advantage is its MT-unsafety, then
> std::regex will never catch up with it.

Yet PCRE is apparently MT-safe:
  http://stackoverflow.com/questions/28769170
so in theory it would be possible to wrap PCRE in a std::regex API
and it would be very fast. (This comment addresses your last sentence
above, but not the sentence preceding it.)

>  So IMO the only realistic alternative is to switch to PCRE, although this,
> of course, just replaces one third party library with another (albeit C
> one).

Okay, then I think we should put this back on the shelf and consider
switching to PCRE when we have the time.