Re: [pygccxml-development] Re: recent changes to pygccxml\pyplusplus

[Allen B. <al...@vr...>]

Matthias Baas wrote:

> Allen Bierbaum wrote:
>
>> I don't know if this would help you or not, but one thing I found 
>> that helped my cache performance greatly (and was on of the reasons I 
>> refactored the code to use md5 signatures) was that I could create a 
>> temporary header file that included all the headers I wanted to 
>> parse.  Then I included that file instead of using a full "project" 
>> of header files.  This made it so gccxml only ran once and it removed 
>> all the redundancy of seeing the same decls from multiple included 
>> headers.  This was able to help me take a parse that was around 2 
>> hours down to about 1.5 minutes.  Overall a very good improvement in 
>> speed. :)
>
>
> Wow, you're right! Using a single temporary header I get the following 
> timings:
>
> Without cache: 12s
> File cache: 4s  (cache size: 3.1MB)
> Dir cache:  2s  (cache size: 2.4MB)
>
> 2 seconds for parsing 222 header files is absolutely ok with me. :)
>
> And now I finally understand what the compilation mode ALL_AT_ONCE as 
> opposed to FILE_BY_FILE actually does (unfortunately, it doesn't use 
> the cache, so it's still more efficient to use FILE_BY_FILE and create 
> a temporary header file manually. This should be fixed eventually and 
> once this is fixed, ALL_AT_ONCE should probably be default).

Interesting.  I would like to hear more about that.  I was never able to 
figure out what ALL_AT_ONCE did let alone get it to work.  I have been 
creating my own temporary file in the wrapper generation script.  Please 
tell me more. :)

-A