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

From: Juergen Hunold (juergen.hunold_at_[hidden])
Date: 2008-04-09 14:14:15

Hi Igor !

On Wednesday 09 April 2008, Igor Nazarenko wrote:
> Jurko,
>
> thanks a lot for looking at the patch, and for the time you put in
> testing the performance.
>
> >   I do not think the patch should be applied to the trunk until
> > someone can present a better use case/usage description where
> > benefits can be seen & reproduced.
>
> I think that any project that uses Boost.Build to install a
> significant number of executables and shared libraries which all
> depend on the same large set of leaf libraries (e.g. Boost) has a
> chance to hit the same problem. Boost itself installs mostly
> libraries with no dependencies, so the initial list of targets to
> install never grows too large.

That rings a bell. Are you using "<install-dependencies>on" in your 
projects ? I'm suspecting this to be the cause of massive delay in my 
project, but was unable to track this down or create a testcase. 

> I'm attaching a synthetic test case that shows the slowdown. To run
> the test, unpack the Jamfile to an empty directory and run bjam in
> that directory.

Amazingly slow :-))

> This test isolates the problem that I have with using BJAM for my own
> project. I produced the list by instrumenting BJAM code to store
> every list it sorts into a file. Thus, the strings being sorted in
> the synthetic test are exactly the same strings that need to be
> sorted in the real project.

I'll try your patch and see if this fixes my problems...

Yours,

Jürgen
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