Re: [Boost-build] Is there any way to prevent Boost.Build fromrecursively scanning header files for #include directives?

Subject: Re: [Boost-build] Is there any way to prevent Boost.Build fromrecursively scanning header files for #include directives?
From: Thorsten Ottosen (thorsten.ottosen_at_[hidden])
Date: 2009-04-29 11:15:54

Vladimir Prus skrev:
> J. van der Wulp wrote:
> 
>> I did not have a look at any of the scanning internals. From a naive
>> look at some level 3 debug logs I got the impression that a lot of
>> scanning work is being done more than once.
>>
>> Is it possible to improve performance by caching scan results? It seems
>> as though a lot of header files are scanned repeatedly. Or is this a
>> consequence differences of preprocessor contexts that are taken into
>> account by the scanner?
>>
>> The Big Question: do bjam/Boost Build v2 developers think that there is
>> room for performance improvement in this regard? Does any substantial
>> performance improvement in scanning come at the expense of correctness?
> 
> Most of the time taken by scanning is time inside Boost.Build code. So, caching
> the 'raw' scanning results does not give much performance advantage. Caching
> at a higher level is considerably harder. My current opinion is that we should
> get Python port to a state where it can build entire Boost C++ Libraries and
> see what performance is in that case. It might be good enough to make any
> further tweaking not necessary.

Why should a python port be faster than a C-based app? Just curious.

-Thorsten