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An MPICH-compatible interface for calling MPI from
StaticCompiler.jl compile_executable'd
standalone Julia executables, building upon the StaticTools.jl approach.
For all purposes other than compiling standalone exacutables, see MPI.jl instead.
Currently, only MPICH-style implementations of libmpi are supported. A relatively complete low-level interface is provided in the Mpich submodule, while the more Julian top-level implementation is still relatively incomplete and under active development.
Note that the functions herein insert LLVM IR that directly calls functions from libmpi.
As such, they will only work when linked against a valid libmpi during compilation.
If you want to use them interactively in the REPL (e.g., for debugging), a valid
libmpi must first have been dlopened with mode RTLD_GLOBAL. By default,
StaticMPI will attempt to automatically dlopen (on init) the libmpi from
MPICH_jll.jl.
If you want to use a different libmpi interactively, just dlopen it before
using StaticMPI
julia> using Libdl
julia> dlopen("/opt/local/lib/mpich-mp/libmpi", RTLD_GLOBAL)
Ptr{Nothing} @0x00007fd5c4c40f40
julia> using StaticMPI
julia> MPI_Init() == MPI_SUCCESS
trueIf any MPI functions herein were somehow ever called without linking to libmpi one way or another, expect segfaults!
julia> using StaticCompiler, StaticTools, StaticMPI
julia> function mpihello(argc, argv)
MPI_Init(argc, argv)
comm = MPI_COMM_WORLD
world_size, world_rank = MPI_Comm_size(comm), MPI_Comm_rank(comm)
printf((c"Hello from ", world_rank, c" of ", world_size, c" processors!\n"))
MPI_Finalize()
end
mpihello (generic function with 1 method)
julia> compile_executable(mpihello, (Int, Ptr{Ptr{UInt8}}), "./";
cflags=`-lmpi -L/opt/local/lib/mpich-mp/`
# -lmpi instructs compiler to link against libmpi.so / libmpi.dylib
# -L/opt/local/lib/mpich-mp/ provides path to my local MPICH installation where libmpi can be found
)
ld: warning: object file (./mpihello.o) was built for newer OSX version (12.0) than being linked (10.13)
"/Users/me/code/StaticTools.jl/mpihello"
shell> mpiexec -np 4 ./mpihello
Hello from 1 of 4 processors!
Hello from 3 of 4 processors!
Hello from 2 of 4 processors!
Hello from 0 of 4 processors!using StaticCompiler, StaticTools, StaticMPI, MPICH_jll
libpath = joinpath(first(splitdir(MPICH_jll.PATH[])), "lib")
# Function to compile
function mpisendrecv(argc, argv)
MPI_Init(argc, argv) == MPI_SUCCESS || error(c"MPI failed to initialize\n")
comm = MPI_COMM_WORLD
world_size, world_rank = MPI_Comm_size(comm), MPI_Comm_rank(comm)
nworkers = world_size - 1
if world_rank == 0
# Gather results on root note
buffer = mfill(0, nworkers)
requests = mfill(MPI_REQUEST_NULL, nworkers)
for i ∈ 1:nworkers
MPI_Irecv(buffer[i:i], i, 10, MPI_COMM_WORLD, requests[i:i])
# Note that this [i:i] syntax only works because contiguous indexing
# of `StaticTools.MallocArray`s returns a view
end
MPI_Waitall(requests)
printf((c"Rank 0 recieved:\n", buffer, c"\n"))
printdlm(c"results.csv", buffer)
free(requests), free(buffer)
else
# Send results back to root node
# Best to use malloc'd things when Sending (or esp. Isend-ing),
# to ensure they won't get unwound before send happens
x = mfill(world_rank)
printf((c"Rank ", world_rank, c", sending ", x[], c"\n"))
MPI_Send(x, 0, 10, comm)
free(x)
end
MPI_Finalize()
end
# Compile it to binary executable
compile_executable(mpisendrecv, (Int, Ptr{Ptr{UInt8}}), "./";
cflags=`-lmpi -L$libpath -Wl,-rpath,$libpath`
# -lmpi instructs compiler to link against libmpi.so / libmpi.dylib
# -L$libpath tells the compiler about the path to libmpi
# -Wl,-rpath,$libpath tells the linker about the path to libmpi (not needed on all systems)
)Since this example linked to the libmpi from MPICH_jll, let's also use the mpiexec from MPICH_jll.
shell> $(MPICH_jll.PATH[])/mpiexec -np 6 ./mpisendrecv
Rank 1, sending 1
Rank 2, sending 2
Rank 3, sending 3
Rank 4, sending 4
Rank 5, sending 5
Rank 0 recieved:
1
2
3
4
5Since we're compiling to standalone executables, we've used the special non-GC-allocating arrays, strings, and IO from StaticTools.jl throughout the above examples.