[Boost-build] [patch review] Re: Help optimizing a slow BJAM build

From: Jurko Gospodnetiæ (jurko.gospodnetic_at_[hidden])
Date: 2008-04-10 20:52:14

   Hi Igor.

 > I'm starting to think that perhaps I'm not building the same BJAM that
 > you are building. Is there a way for me to check out exactly the same
 > version of the trunk that you are using? Also, can you send the
 > commands that you used to build BJAM?

   OK, it seems I must have done something wrong the first time. Sorry...

   I now deleted all the builds and rebuilt them again and now I get 
timings matching your own - both with the original test Jamfile and the 
new one you sent.

   Time to change my vote and say that the patch should be applied to 
the trunk. :-) And possibly a test added based on the latest example to 
guard against any regressions. Volodya, should I do this or should we 
wait for more opinions?

   I retested the new builds with one of our own big projects but it 
seems that we just do not hit this speedup scenario there and timings 
remain the same. Ah well... :-)

 >> >    Directly running your test case (even after adding an empty
 >> >  Jamroot file) on my machine did nothing and exited instantly -
 >> >  most likely due to a memory allocation error (returned error code
 >> >  is -1073741819). To make it work I needed to remove the last 3709
 >> >  entries.
 >
 > This is weird. Using the BJAM which was shipped with Boost 1.34.1, I
 > see it's memory footprint staying well under 30MB. I ran it using
 > "bjam -f Jamfile".

   Ok, this must be something related to my machine and/or compiler 
(MSVC 7.1). I now repeated the original test with newly build bjam 
executables and they still fail on the original test sample. But I have 
not encountered this problem in practice and do not have the time to go 
tracking it down in more detail now just for the fun of it :-(.

 > thanks again for looking into this!

   My pleasure! :-) Although I do not think you should look at this as a 
totally selfless act, :-))) and I guess I should be thanking you as 
anything you do to make Boost Build faster - makes it faster for us as 
well... :-)))

   Best regards,
     Jurko Gospodnetiæ