On 00:23 Mon 31 Dec , Philipp Kraus wrote:
The algorithm has got a "initialization", so the core 0 must send an identifier to all other cores and each core can initialize all data for the algorithm locally and independend from the other cores. So I need only the exchange of the ID. After all cores have finished their local initialization the cores must be "synchronized". So I named this initialization "preexecution". For the algorithm the time length of this preexecutation is irrelevant, so I need only that each core gets the ID from core 0 and after initialization the core must be switched into a "synchronized communication".
Ah, I get it. Thanks!
I do it at the moment with:
while (thread_is_running) {
if (!l_mpicom.rank()) for(std::size_t i=1; i < l_mpicom.size(); ++i) l_mpicom.isend(i, 666, l_task.getID()); else if (boost::optionalmpi::status l_status = l_mpicom.iprobe(0, 666)) { std::size_t l_taskid = 0; l_mpicom.recv( l_status->source(), l_status->tag(), l_taskid ); } }
You could rebuild the binary tree communication scheme I've illustrated using Boost MPI (I'm too lazy). I'm pretty sure calling isend() without ever waiting for completion is illegal according to the MPI standard and will result in a memory leak (plus the code won't scale thanks to the for loop).
I don't see a problem !? While loop checks on each iteration if there is a message in the MPI queue, if not I can do other things. If a message in the queue, I read them, and store it in my local variable and work with the value later (not shown here in the example).
The problem is that you never seem to call MPI_Wait() for the requests generated by MPI_Isend (or Boost MPI's isend(), which is in fact "just" a convenient wrapper). Let me quote the the man page: "Nonblocking calls allocate a communication request object" These requests are only freed after calling MPI_Wait for them. Hence the memory leak.
Thanks for the great discussion
You're welcome. :-) Cheers -Andreas -- ========================================================== Andreas Schäfer HPC and Grid Computing Chair of Computer Science 3 Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany +49 9131 85-27910 PGP/GPG key via keyserver http://www.libgeodecomp.org ========================================================== (\___/) (+'.'+) (")_(") This is Bunny. Copy and paste Bunny into your signature to help him gain world domination!