36 lines
1.2 KiB
Plaintext
36 lines
1.2 KiB
Plaintext
[section:threading Threads]
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There are an increasing number of hybrid parallel applications that mix
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distributed and shared memory parallelism. To know how to support that model,
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one need to know what level of threading support is guaranteed by the MPI
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implementation. There are 4 ordered level of possible threading support described
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by [enumref boost::mpi::threading::level mpi::threading::level].
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At the lowest level, you should not use threads at all, at the highest level, any
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thread can perform MPI call.
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If you want to use multi-threading in your MPI application, you should indicate
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in the environment constructor your preferred threading support. Then probe the
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one the library did provide, and decide what you can do with it (it could be
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nothing, then aborting is a valid option):
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#include <boost/mpi/environment.hpp>
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#include <boost/mpi/communicator.hpp>
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#include <iostream>
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namespace mpi = boost::mpi;
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namespace mt = mpi::threading;
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int main()
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{
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mpi::environment env(mt::funneled);
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if (env.thread_level() < mt::funneled) {
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env.abort(-1);
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}
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mpi::communicator world;
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std::cout << "I am process " << world.rank() << " of " << world.size()
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<< "." << std::endl;
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return 0;
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}
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[endsect:threading]
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