Missing -lgomp when installing

[wzchen]

I get the following output when I try to run make in the python directory. Do you know what may be wrong?

Williams-MacBook-Air:python william$ make
g++ -Wall -O3 -msse2  -Wno-unknown-pragmas -fopenmp -fPIC -pthread -lm  -shared -o libxgboostpy.so xgboost_python.cpp
In file included from xgboost_python.cpp:3:
In file included from ./../regrank/xgboost_regrank.h:12:
In file included from ./../regrank/xgboost_regrank_eval.h:13:
./../regrank/../utils/xgboost_omp.h:13:2: warning: "OpenMP is not available, compile to single thread code" [-W#warnings]
#warning "OpenMP is not available, compile to single thread code"
 ^
1 warning generated.
ld: library not found for -lgomp
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [libxgboostpy.so] Error 1

[antinucleon]

You need to install OpenMP library before build XGBoost. You can search in Google to find how to install OpenMP on MacOSX

[tqchen]

This is because your compiler does not support OpenMP. While the linker tries to link OpenMP -_-

[tqchen]

This seems due to the fact that the compiler is not configured correctly(otherwise -fopenmp will be ignored), one way is to use single thread mode, remove -fopenmp in the Makefile, this will give you a single thread version of xgboost. Or you can try to install OpenMP

[tqchen]

Maybe we should add instructions to the wiki

[wzchen]

@tqchen thank you! removing the -fopenmp flag worked. I will try to install OpenMP later.