openMP support in Windows?

[Joon Ro]

Hi,

I am trying to compile my cython code with openmp support in Windows 8 with

```python

    extra_compile_args=['-fopenmp'],
    extra_link_args=['-fopenmp'],
```

in my setup.py file, but I've got ``fatal error: omp.h: No such file or directory``. What should I do to make it compile?

I'm using Anaconda 1.4.

Best,
Joon

[Ilan Schnell]

Hi Joon,
Anaconda comes with MinGW on Windows.  This is set to the default compiler,
in the file C:\Anaconda\Lib\distutils\distutils.cfg
If you google for "mingw openmp", you'll find that this is a common problem people run into, e.g.:
http://stackoverflow.com/questions/8104560/how-to-set-up-openmp

Hope that helps

- Ilan

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[David Hirschfeld]

AFAIK MinGW doesn’t come with openmp by default so if it’s not included in the Anaconda version you’ll probably have to find the correct installer from the MinGW site and install it.

 

On Windows I’d generally recommend using TDM GCC (http://tdm-gcc.tdragon.net/) which has the option to automatically include openmp support and takes away the hassle of trying to manually find/install the correct packages and dependencies from the MinGW site.

 

-Dave

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[Joon Ro]

On Wednesday, March 27, 2013 3:11:16 AM UTC-5, David Hirschfeld wrote:

On Windows I’d generally recommend using TDM GCC (http://tdm-gcc.tdragon.net/) which has the option to automatically include openmp support and takes away the hassle of trying to manually find/install the correct packages and dependencies from the MinGW site.

Thanks a lot! I have just installed TDM GCC and I was able to compile my cython code with

-fopenmp flag.

-Joon

 

[jfc.h...@gmail.com]

I'm sure this is a simple matter, but what does the disutils.cfg file expect as a value so that it will use the TDM GCC compiler?
And after installing TDM GCC, are any other steps required than editing the compiler value in the distutils.cfg file?

[Joon Ro]

I actually did not have to change anything. Once I installed TDM GCC, when I compiled my cython moduel, the compiler from TDM GCC was used automatically. I guess it modified the PATH env variable.

-Joon

[Jon Herman]

Hmm, it seems that works for me as well, thanks! I was reluctant to just add it to the path since Anaconda's gcc.bat is already in there. It seems to be running alright for me, but if anyone knows if this could create issues and/or how to do this more correctly, I would very much appreciate to hear about that.

Thanks,

Jon

[Majid al-Dosari]

just curious...were you compiling on 64bit windows? if so, were you able to successfully compile your c-extension?

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[garyfa...@gmail.com]

Hello all, 

we are having the same problem and the suggested solution doesn't work for us. We are using Windows 8. 

After installing TDM GCC (version 4.8.1) we get cannot find libgomp.spec then we found somewhere online and downloaded that file. After that we got another error

c:/tdm-gcc-64/bin/../lib/gcc/x86_64-w64-mingw32/4.8.1/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lgomp

Having cython with parallelization is crucial for our library found in dipy.org as we deal with very large datasets and we need to exploit all the cores in our system to analyse them. We loved

and suggested Anaconda to our users because it makes installing numpy, scipy and cython easier. But it seems that the Cython installation is not complete without parallelization.

We would appreciate any help and we hope we can work together to solve this important issue.

Best wishes,

Eleftherios and Jesus-Omar

on behalf of the Dipy developers

[Joon Ro]

On Wednesday, March 12, 2014 7:18:25 PM UTC-5, Eleftherios Garyfallidis wrote:

Hello all, 

we are having the same problem and the suggested solution doesn't work for us. We are using Windows 8. 

After installing TDM GCC (version 4.8.1) we get cannot find libgomp.spec then we found somewhere online and downloaded that file. After that we got another error

I have `libgomp.spec` in `C:\TDM-GCC-64\lib\gcc\x86_64-w64-mingw32\4.8.1`. Did you check openmp support when you install TDM-GCC? Please see the instructions that I wrote: http://docs-windows.readthedocs.org/en/latest/devel.html#mingw-with-openmp-support.

Please let me know if it does not work.

-Joon

[Eleftherios Garyfallidis]

Hello,

Thank you for your response and for writing the blog. It does work for us now too.  Indeed we didn't see that there was an option for openmp it was a bit misleading to find this because everything look selected but still you had to go in the tree and select openmp. 

It would be amazing if anaconda could install tdm-gcc automatically and/or support openmp from default. Is there a plan for this?

[Joon Ro]

On Thursday, March 13, 2014 10:33:46 AM UTC-5, Eleftherios Garyfallidis wrote:

Thank you for your response and for writing the blog. It does work for us now too.  Indeed we didn't see that there was an option for openmp it was a bit misleading to find this because everything look selected but still you had to go in the tree and select openmp. 

I'm glad that it worked for you. Yes it can be confusing - I should try to add this instruction to Cython documentation.

-Joon

[Yuxiang Wang]

I am wondering why Anaconda does not come with OpenMP included - I know it is not by default in MinGW, but we could

a) Use TDM-GCC

b) (Or better yet) use this one used for numpy/scipy https://github.com/numpy/numpy/wiki/Mingw-static-toolchain

Shawn