M1 Mac compile Mex file with OpenMP

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I tried to compile mex function in M1 mac with matlab 2022a and matlab 2022a beta, it works well without openmp. But When I tried to include omp.h, error occurs.
Step1, I installed openmp with xcode,
curl -O https://mac.r-project.org/openmp/openmp-13.0.0-darwin21-Release.tar.gz
sudo tar fvxz openmp-13.0.0-darwin21-Release.tar.gz -C /
test1.cpp
#include <omp.h>
#include <iostream>
int main() {
#pragma omp parallel
std::cout<<"Hello from thread: "<< omp_get_thread_num()<< "nthreads: " << omp_get_num_threads() << "\n";
}
I can compile test1.cpp with (-Xpreprocessor also works):
clang++ -Xclang -fopenmp -lomp test1.cpp
The results looks good:
Hello from thread 0, nthreads 8
Hello from thread 2, nthreads 8
Hello from thread 4, nthreads 8
Hello from thread 3, nthreads 8
Hello from thread 5, nthreads 8
Hello from thread 7, nthreads 8
Hello from thread 1, nthreads 8
Hello from thread 6, nthreads 8
Step2, I tried to build a test function with matlab
test2.cpp
If I use #include "omp.h", I will get: error: "omp.h" file not found, therefore I used absolute path
#include "mex.h"
#include "/usr/local/include/omp.h"
void mexFunction(int nlhs, mxArray* plhs[], int nrhs, const mxArray* prhs[]) {
#pragma omp parallel
mexPrintf("Hello from thread %d, nthreads %d\n", omp_get_thread_num(), omp_get_num_threads());
mexPrintf("hello world!\n");
}
mex command I used
matlab 2022a beta
mex -v CXXFLAGS='$CXXFLAGS -Xclang -fopenmp -arch arm64' LDFLAGS='$LDFLAGS -I/usr/local/include -L/usr/local/lib -lomp -mmacosx-version-min=12.4' -I'usr/local/include' -L'usr/local/lib' test2.cpp
matlab 2022a
mex -v CXXFLAGS='$CXXFLAGS -Xclang -fopenmp -arch x86_64' LDFLAGS='$LDFLAGS -I/usr/local/include -L/usr/local/lib -lomp -mmacosx-version-min=12.4' -I'usr/local/include' -L'usr/local/lib' test.cpp
MEX completed successfully, but if I run the test2.mexmaci64 or test2.mexmaca64, maltab stopped immediately.
If I commented this line,
#pragma omp parallel
The results became:
Hello from thread 0, nthreads 1
hello world!
Supported compiler on mac is Xcode 13.x and my clang --version is:
Apple clang version 13.1.6 (clang-1316.0.21.2.5)
Target: arm64-apple-darwin21.5.0
  1 Comment
shuang zhou
shuang zhou on 18 Jul 2022
Update:
test.cpp (absolute path of "omp.h" is not required)
#include "mex.h"
#include "omp.h"
void mexFunction(int nlhs, mxArray* plhs[], int nrhs, const mxArray* prhs[]) {
#pragma omp parallel
mexPrintf("Hello from thread %d, nthreads %d\n", omp_get_thread_num(), omp_get_num_threads());
mexPrintf("hello world!\n");
}
mex command:
mex -v CXX_FLAGS="-Xclang -fopenmp" LDFLAGS="$LDFLAGS -lomp" -I/usr/local/include test.cpp
This command works with 1 thread, this mex command will generate 3 commands for clang++:
/usr/bin/xcrun -sdk macosx12.3 clang++ -c -DMATLAB_DEFAULT_RELEASE=R2017b -DUSE_MEX_CMD -DMATLAB_MEX_FILE -I"/usr/local/include" -I"/Applications/MATLAB_R2022a.app/extern/include" -I"/Applications/MATLAB_R2022a.app/simulink/include" -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -O2 -fwrapv -DNDEBUG "my_path/test.cpp" -o /var/folders/36/h6gn6pqj20g79jrplzyd5y800000gn/T/mex_35678585508292_17546/test.o
/usr/bin/xcrun -sdk macosx12.3 clang++ -c -DMATLAB_DEFAULT_RELEASE=R2017b -DUSE_MEX_CMD -DMATLAB_MEX_FILE -I"/usr/local/include" -I"/Applications/MATLAB_R2022a.app/extern/include" -I"/Applications/MATLAB_R2022a.app/simulink/include" -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -O2 -fwrapv -DNDEBUG "/Applications/MATLAB_R2022a.app/extern/version/cpp_mexapi_version.cpp" -o /var/folders/36/h6gn6pqj20g79jrplzyd5y800000gn/T/mex_35678585508292_17546/cpp_mexapi_version.o
/usr/bin/xcrun -sdk macosx12.3 clang++ -Wl,-twolevel_namespace -undefined error -arch x86_64 -mmacosx-version-min=10.15 -Wl,-syslibroot,/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -framework Cocoa -bundle -stdlib=libc++ -lomp -O -Wl,-exported_symbols_list,"/Applications/MATLAB_R2022a.app/extern/lib/maci64/mexFunction.map" -Wl,-exported_symbols_list,"/Applications/MATLAB_R2022a.app/extern/lib/maci64/c_exportsmexfileversion.map" -Wl,-U,_mexCreateMexFunction -Wl,-U,_mexDestroyMexFunction -Wl,-U,_mexFunctionAdapter -Wl,-exported_symbols_list,"/Applications/MATLAB_R2022a.app/extern/lib/maci64/cppMexFunction.map" /var/folders/36/h6gn6pqj20g79jrplzyd5y800000gn/T/mex_35678585508292_17546/test.o /var/folders/36/h6gn6pqj20g79jrplzyd5y800000gn/T/mex_35678585508292_17546/cpp_mexapi_version.o -L"/Applications/MATLAB_R2022a.app/bin/maci64" -lmx -lmex -lmat -L"/Applications/MATLAB_R2022a.app/extern/bin/maci64" -lMatlabDataArray -lMatlabEngine -o test.mexmaci64
-Xclang -fopenmp did not present in these cmds, therefore the test.mexmaci64 can only use 1 thread.
If I add -fopenmp:
mex -v CXX_FLAGS="-Xclang -fopenmp" LDFLAGS="$LDFLAGS -lomp" CXXOPTIMFLAGS="$CXXOPTIMFLAGS -Xclang -fopenmp" -I/usr/local/include test.cpp
Matlab will crash when I run test().
I modified the mex derived 3 commands and find openmp in the first one will crash matlab:
/usr/bin/xcrun -sdk macosx12.3 clang++ -c -DMATLAB_DEFAULT_RELEASE=R2017b -DUSE_MEX_CMD -DMATLAB_MEX_FILE -I"/usr/local/include" -I"/Applications/MATLAB_R2022a.app/extern/include" -I"/Applications/MATLAB_R2022a.app/simulink/include" -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -O2 -fwrapv -DNDEBUG -Xclang -fopenmp -lomp "my_path/test.cpp" -o /var/folders/36/h6gn6pqj20g79jrplzyd5y800000gn/T/mex_35678585508292_17546/test.o
It looks like matlab do not support openmp well, but I know matlab do support openmp with mex.
I tried a simple function test3.m
function test3(n)
parfor i = 1:n
fprintf('i = %d \n',i);
end
end
Then use matlab coder to generate mex function, I found the cmds used in matlab coder
[1/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" /Applications/MATLAB_R2022a.app/extern/version/cpp_mexapi_version.cpp -o build/maci64/cpp_mexapi_version.o
[2/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" test3_data.cpp -o build/maci64/test3_data.o
[3/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" interface/_coder_test3_info.cpp -o build/maci64/_coder_test3_info.o
[4/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" rt_nonfinite.cpp -o build/maci64/rt_nonfinite.o
[5/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" test3_initialize.cpp -o build/maci64/test3_initialize.o
[6/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" eml_int_forloop_overflow_check.cpp -o build/maci64/eml_int_forloop_overflow_check.o
[7/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" interface/_coder_test3_mex.cpp -o build/maci64/_coder_test3_mex.o
[8/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" test3_terminate.cpp -o build/maci64/test3_terminate.o
[9/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" interface/_coder_test3_api.cpp -o build/maci64/_coder_test3_api.o
[10/11] /usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/mypath" -I "./interface" -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test3_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" test3.cpp -o build/maci64/test3.o
[11/11] /usr/bin/xcrun -sdk macosx12.3 clang++ build/maci64/test3_data.o build/maci64/rt_nonfinite.o build/maci64/test3_initialize.o build/maci64/test3_terminate.o build/maci64/test3.o build/maci64/_coder_test3_api.o build/maci64/_coder_test3_mex.o build/maci64/eml_int_forloop_overflow_check.o build/maci64/_coder_test3_info.o build/maci64/cpp_mexapi_version.o -Wl,-twolevel_namespace -undefined error -arch x86_64 -mmacosx-version-min=10.15 -Wl,-syslibroot,/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -framework Cocoa -bundle -stdlib=libc++ -L"/Applications/MATLAB_R2022a.app/bin/maci64" -lmx -lmex -lmat -L"/Applications/MATLAB_R2022a.app/extern/bin/maci64" -lMatlabDataArray -lMatlabEngine -Wl,-rpath,@loader_path -o test3_mex.mexmaci64 -lemlrt -lcovrt -lut -lmwmathutil -fPIC -L"/Applications/MATLAB_R2022a.app/sys/os/maci64" -liomp5
run test3_mex(int32(16)), I got this result:
i = 15
i = 16
i = 11
i = 12
i = 13
i = 14
i = 9
i = 10
i = 1
i = 2
i = 7
i = 8
i = 5
i = 6
i = 3
i = 4
Then, I changed the path and filenames in those cmds:
system('/usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" /Applications/MATLAB_R2022a.app/extern/version/cpp_mexapi_version.cpp -o cpp_mexapi_version.o');
system('/usr/bin/xcrun -sdk macosx12.3 clang++ -fno-common -arch x86_64 -mmacosx-version-min=10.15 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -fobjc-arc -std=c++11 -stdlib=libc++ -DMATLAB_MEX_FILE -O2 -fwrapv -DNDEBUG -fvisibility=hidden -std=c++11 -I "." -I "/Applications/MATLAB_R2022a.app/extern/include" -I "." -DMODEL=test_mex -DMW_NEEDS_VERSION_H -c -fPIC -Xpreprocessor -fopenmp -I "/Applications/MATLAB_R2022a.app/toolbox/eml/externalDependency/omp/maci64/include" -DOpenMP_omp_LIBRARY="/Applications/MATLAB_R2022a.app/sys/os/maci64/libiomp5.dylib" test.cpp -o test.o');
system('/usr/bin/xcrun -sdk macosx12.3 clang++ test.o cpp_mexapi_version.o -Wl,-twolevel_namespace -undefined error -arch x86_64 -mmacosx-version-min=10.15 -Wl,-syslibroot,/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -framework Cocoa -bundle -stdlib=libc++ -L"/Applications/MATLAB_R2022a.app/bin/maci64" -lmx -lmex -lmat -L"/Applications/MATLAB_R2022a.app/extern/bin/maci64" -lMatlabDataArray -lMatlabEngine -Wl,-rpath,@loader_path -o test_mex.mexmaci64 -lemlrt -lcovrt -lut -lmwmathutil -fPIC -L"/Applications/MATLAB_R2022a.app/sys/os/maci64" -liomp5');
And crashed again.

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Accepted Answer

shuang zhou
shuang zhou on 19 Jul 2022
Edited: shuang zhou on 19 Jul 2022
The problem is caused by print out functions,
mexPrintf function, stream out function(https://www.mathworks.com/help/matlab/matlab_external/displaying-output-in-matlab-command-window.html) or even other output functions cannot be in parallel structure!!!
mexPrintf and all other memory allocate function are thread unsafe. https://www.mathworks.com/matlabcentral/answers/418782-thread-safety-of-mx-mex-functions
Wrong usage (this will crash):
#include "mex.h"
#include "omp.h"
void mexFunction(int nlhs, mxArray* plhs[], int nrhs, const mxArray* prhs[]) {
#pragma omp parallel for
for(int p = 0; p<16; ++p){
mexPrintf("p = %d\n",p);// output function should not in parallel structure!!
}
}
Correct usage test1.cpp:
#include "mex.h"
#include "omp.h"
void mexFunction(int nlhs, mxArray* plhs[], int nrhs, const mxArray* prhs[]) {
double sum{};
#pragma omp parallel for reduction(+: sum)
for(int p = 0; p<100000000; ++p){
sum += (double)(p)*(double)(p);
}
mexPrintf("sum = %f\n",sum);
}
Compile:
mex CXX_FLAGS="-Xclang -fopenmp" LDFLAGS="$LDFLAGS -lomp" CXXOPTIMFLAGS="$CXXOPTIMFLAGS -Xclang -fopenmp" -I/usr/local/include test1.cpp
benchmark:
tic;test1();toc;
// with openmp 0.02s @M1 pro 8 core
// without openmp 0.1s @M1 pro 8 core
In summary:
step1 install openmp, run this in terminal (https://mac.r-project.org/openmp/):
curl -O https://mac.r-project.org/openmp/openmp-13.0.0-darwin21-Release.tar.gz
sudo tar fvxz openmp-13.0.0-darwin21-Release.tar.gz -C /
step2 compile with -Xclang -fopenmp and -lomp
mex CXX_FLAGS="-Xclang -fopenmp" LDFLAGS="$LDFLAGS -lomp" CXXOPTIMFLAGS="$CXXOPTIMFLAGS -Xclang -fopenmp" -I/usr/local/include test1.cpp
  2 Comments
shuang zhou
shuang zhou on 19 Jul 2022
Matlab R2022a could be not stable, sometimes openmp works, something it will crash(after installation of new toolbox). Matalab R2022a beta is stable.
Calling a magic function could stablize Matlab R2022a.
How to get a magic function:
test.m
function test(n)
parfor i = 1:n
fprintf('i = %d \n',i);
end
end
Convert to mex function with matlab coder (input should be int32 1x1 scalar), run the mex function
test_mex(int32(n));
shuang zhou
shuang zhou on 13 Aug 2022
the magic function can be found in my repo :https://github.com/civerjia/Proton-Bragg-Peak-Fit
go to the utils folder and run ifMacCrashed()

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