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Subject: Re: [Boost-build] Threading with vacpp toolset
From: Vladimir Prus (ghost_at_[hidden])
Date: 2010-11-27 01:34:48

On Friday, November 26, 2010 21:12:10 K. Noel Belcourt wrote:
> Hi,
> With the vacpp toolset, we build single threaded by default but when
> we enable MPI, a few Boost libraries are built threading=multi due to
> the dependence on MPI. What's strange is that the compile lines for
> these libraries look like this:
> qpic=large -qcpluscmt -qNOOPTimize -qnoinline -g -qfullpath -qeh -
> qrtti -I".." -I"/projects/sierra/dawn/openmpi-1.4.2/include" -o "/
> scratch2/kbelco/boost/results/boost/bin.v2/libs/graph_parallel/test/
> adjlist_build_test-2.test/vacpp-10.1/debug/threading-multi/
> adjlist_build_test.o" "../libs/graph_parallel/test/
> adjlist_build_test.cpp"
> Notice the single threaded compiler (xlC) followed by the multi-
> threaded compiler (xlC_r).
> The problem seems to be in the vacpp.jam file where the compiler is
> selected based on the threading model.
> flags vacpp VA_CXX_COMPILER <threading>single : xlC ;
> flags vacpp VA_CXX_COMPILER <threading>multi : xlC_r ;
> It seems that when we set the flag for the multi-threaded compiler,
> we should replace the existing compiler (xlC) rather than append on a
> new compiler (xlC_r).

Actually, the flags are evaluated once for each action executed, and therefore
no replace should be necessary. The behaviour you see seems only possible
if somehow, the property set for an action has both <threading>single and
<threading>multi. Can you send me (offlist) the output of bjam
with --debug-building (possiblity adding --with-whatever-library-is-causing-
problem, which is graph_parallel, right?)

- Volodya

Vladimir Prus

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