Fix ray import error

[wdirons]

To fix the ray error with rpath, I moved the compilers from the build section of
requirements to the host section of requirements. The conda documentation says
that any shared libraries that you need to link against in your build should be
in the host section. This solved the rpath issue.

I reordered the build section to be the above the host section for to be
consistent across recipes.

This PR uses the common build_scripts now for ray-feedstock

[wdirons]

Please read the commit message above to understand the change I made. (Because I reordered the two sections, the difference is hard to see)

Before and after test with the old/new packages

$ python -c "import ray"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/mnt/pai/home/wdirons/anaconda3/envs/testray/lib/python3.7/site-packages/ray/__init__.py", line 25, in <module>
    CDLL(so_path, ctypes.RTLD_GLOBAL)
  File "/mnt/pai/home/wdirons/anaconda3/envs/testray/lib/python3.7/ctypes/__init__.py", line 364, in __init__
    self._handle = _dlopen(self._name, mode)
OSError: /lib64/libstdc++.so.6: version `GLIBCXX_3.4.21' not found (required by /mnt/pai/home/wdirons/anaconda3/envs/testray/lib/python3.7/site-packages/ray/_raylet.so)


$ conda install conda-recipes/ray-feedstock/build_artifacts/linux-ppc64le/ray-0.8.1-py37h1d8a796_2.tar.bz2
Preparing transaction: done
Verifying transaction: done
Executing transaction: done


$ python -c "import ray"
WARNING: Not monitoring node memory since `psutil` is not installed. Install this with `pip install psutil` (or ray[debug]) to enable debugging of memory-related crashes.

Comparison of a extract of the conda .tar.bz2 files:

ray-0.8.1-py37h1d8a796_1.tar.bz2:

$ grep binary info/has_prefix
<nothing>

ray-0.8.1-py37h1d8a796_2.tar.bz2:

$ grep binary info/has_prefix
/home/conda/feedstock_root/build_artifacts/ray_1587667295899/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placeho binary lib/python3.7/site-packages/ray/_raylet.so
/home/conda/feedstock_root/build_artifacts/ray_1587667295899/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placeho binary lib/python3.7/site-packages/ray/core/src/plasma/plasma_store_server
/home/conda/feedstock_root/build_artifacts/ray_1587667295899/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placeho binary lib/python3.7/site-packages/ray/core/src/ray/gcs/redis_module/libray_redis_module.so
/home/conda/feedstock_root/build_artifacts/ray_1587667295899/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placeho binary lib/python3.7/site-packages/ray/core/src/ray/raylet/raylet
/home/conda/feedstock_root/build_artifacts/ray_1587667295899/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placeho binary lib/python3.7/site-packages/ray/core/src/ray/raylet/raylet_monitor
/home/conda/feedstock_root/build_artifacts/ray_1587667295899/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placeho binary lib/python3.7/site-packages/ray/core/src/ray/thirdparty/redis/src/redis-server
/home/conda/feedstock_root/build_artifacts/ray_1587667295899/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placeho binary lib/python3.7/site-packages/ray/streaming/_streaming.so

[wdirons]

And of course I forgot to update .travis.yaml :(

[jayfurmanek]

in .travis.yaml, the new way is:

os: linux
arch: ppc64le

[jayfurmanek]

just linux here

[wdirons]

Sorry, I had cut and pasted the .travis.yml for the last ray PR. Should be fixed now.

[npanpaliya]

Thanks Billy for fixing this.

[hartb]

Huh. I wonder why we don't see this all over the place. Surely any compiled C++ code must need libstdc++.so.6 and the normal conda build machinery should get an RPATH to the conda version of that into objects produced by the recipe. Maybe there's something peculiar about the ray recipe that interferes with the normal mechanism.

A bit weird, but if it works, then I'm OK with it.

[jayfurmanek]

Did you try conda run_exports syntax:
https://docs.conda.io/projects/conda-build/en/latest/resources/define-metadata.html#export-runtime-requirements

or shared lib whitelist?:
https://docs.conda.io/projects/conda-build/en/latest/resources/define-metadata.html#whitelisting-shared-libraries

[wdirons]

Using

+  run_exports:
+    - {{ compiler('c') }}
+    - {{ compiler('cxx') }}

I got same /lib64/libstdc++.so.6: version GLIBCXX_3.4.21 not found` error.

Trying whitelist now.

[wdirons]

I'll submit a new PR with a better fix.

[den-run-ai]

@wdirons @jayfurmanek @hartb looks like related issue?

#272