latest python built statically creates VTK - matplotlib issues.

[danlipsa]

Issue:
We are building VTK using conda forge on Mac. With the latest python we get:
(test) [~]$ python
Python 3.6.7 | packaged by conda-forge | (default, Nov 20 2018, 18:37:09)
[GCC 4.2.1 Compatible Clang 4.0.1 (tags/RELEASE_401/final)] on darwin
Type "help", "copyright", "credits" or "license" for more information.

import vtk
Fatal Python error: PyThreadState_Get: no current thread

Abort trap: 6

The VTK package that causes problems is VTK - matplotlib, a way to draw matplotlib plots from VTK. This package needs another instance of python. Because the latest python package links statically with libpython we end-up with two python versions = one from the the statically linked python and one brought it by VTK for using it with matplotlib.

Current python is linked statically

(test) [~]$ otool -L /Users/danlipsa/anaconda3/envs/test/bin/python
/Users/danlipsa/anaconda3/envs/test/bin/python:
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1197.1.1)
(test) [~]$ python --version
Python 3.6.7
(test) [~]$ conda list | grep python
ipython                   7.2.0           py36h24bf2e0_1000    conda-forge
ipython_genutils          0.2.0                      py_1    conda-forge
python                    3.6.7             h4a56312_1001    conda-forge
(test) [~]$ 

Previous python was built dynamically and that works with VTK-matplotlib

(nightly) [~/projects/VTK/src/Rendering (master %=)]$ otool -L /Users/danlipsa/anaconda3/envs/nightly/bin/python
/Users/danlipsa/anaconda3/envs/nightly/bin/python:
	/usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 120.0.0)
	/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1153.18.0)
	@rpath/libpython3.6m.dylib (compatibility version 3.6.0, current version 3.6.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1213.0.0)

python                    3.6.6                h5001a0f_0    conda-forge

Also, python 2.7 is linked dynamically and that works.

Environment (conda list):

(test) [~]$ conda list

packages in environment at /Users/danlipsa/anaconda3/envs/test:

Name Version Build Channel

appnope 0.1.0 py36_1000 conda-forge
backcall 0.1.0 py_0 conda-forge
blas 1.0 mkl
bzip2 1.0.6 h1de35cc_1002 conda-forge
ca-certificates 2018.11.29 ha4d7672_0 conda-forge
certifi 2018.11.29 py36_1000 conda-forge
decorator 4.3.2 py_0 conda-forge
ffmpeg 4.1 heb45b42_1000 conda-forge
freetype 2.9.1 h597ad8a_1005 conda-forge
future 0.17.1 py36_1000 conda-forge
gettext 0.19.8.1 hcca000d_1001 conda-forge
gmp 6.1.2 h0a44026_1000 conda-forge
gnutls 3.6.5 h53004b3_1001 conda-forge
intel-openmp 2019.1 144
ipython 7.2.0 py36h24bf2e0_1000 conda-forge
ipython_genutils 0.2.0 py_1 conda-forge
jedi 0.13.2 py36_1000 conda-forge
libcxx 7.0.0 h2d50403_2 conda-forge
libffi 3.2.1 h0a44026_1005 conda-forge
libgfortran 3.0.1 h93005f0_2
libiconv 1.15 h1de35cc_1004 conda-forge
libpng 1.6.36 ha441bb4_1000 conda-forge
llvm-meta 7.0.0 0 conda-forge
mkl 2019.1 144
mkl_fft 1.0.10 py36h1de35cc_1 conda-forge
mkl_random 1.0.2 py36h1702cab_2 conda-forge
ncurses 6.1 h0a44026_1002 conda-forge
nettle 3.4.1 h1de35cc_1002 conda-forge
numpy 1.15.4 py36hacdab7b_0
numpy-base 1.15.4 py36h6575580_0
openh264 1.8.0 hd9629dc_1000 conda-forge
openssl 1.0.2p h1de35cc_1002 conda-forge
parso 0.3.2 py_0 conda-forge
pexpect 4.6.0 py36_1000 conda-forge
pickleshare 0.7.5 py36_1000 conda-forge
pip 19.0.1 py36_0 conda-forge
prompt_toolkit 2.0.7 py_0 conda-forge
ptyprocess 0.6.0 py36_1000 conda-forge
pygments 2.3.1 py_0 conda-forge
python 3.6.7 h4a56312_1001 conda-forge
readline 7.0 hcfe32e1_1001 conda-forge
setuptools 40.6.3 py36_0 conda-forge
six 1.12.0 py36_1000 conda-forge
sqlite 3.26.0 h1765d9f_1000 conda-forge
tk 8.6.9 ha441bb4_1000 conda-forge
traitlets 4.3.2 py36_1000 conda-forge
vtk-cdat 8.2.0.rc2.289.8.0.2019.01.28.16.04.g14c0bb696d py36h3a4d124_0 danlipsa
wcwidth 0.1.7 py_1 conda-forge
wheel 0.32.3 py36_0 conda-forge
x264 1!152.20180717 h1de35cc_1001 conda-forge
xz 5.2.4 h1de35cc_1001 conda-forge
zlib 1.2.11 h1de35cc_1004 conda-forge

Details about conda and system ( conda info ):

(test) [~]$ conda info

 active environment : test
active env location : /Users/danlipsa/anaconda3/envs/test
        shell level : 1
   user config file : /Users/danlipsa/.condarc

populated config files : /Users/danlipsa/.condarc
conda version : 4.5.12
conda-build version : 3.13.0
python version : 3.6.4.final.0
base environment : /Users/danlipsa/anaconda3 (writable)
channel URLs : https://conda.anaconda.org/doutriaux1/osx-64
https://conda.anaconda.org/doutriaux1/noarch
https://conda.anaconda.org/conda-forge/osx-64
https://conda.anaconda.org/conda-forge/noarch
https://repo.anaconda.com/pkgs/main/osx-64
https://repo.anaconda.com/pkgs/main/noarch
https://repo.anaconda.com/pkgs/free/osx-64
https://repo.anaconda.com/pkgs/free/noarch
https://repo.anaconda.com/pkgs/r/osx-64
https://repo.anaconda.com/pkgs/r/noarch
https://repo.anaconda.com/pkgs/pro/osx-64
https://repo.anaconda.com/pkgs/pro/noarch
package cache : /Users/danlipsa/anaconda3/pkgs
/Users/danlipsa/.conda/pkgs
envs directories : /Users/danlipsa/anaconda3/envs
/Users/danlipsa/.conda/envs
platform : osx-64
user-agent : conda/4.5.12 requests/2.18.4 CPython/3.6.4 Darwin/18.2.0 OSX/10.14.2
UID:GID : 501:20
netrc file : None
offline mode : False

[jjhelmus]

The change from dynamic linking to static linking was intentional. Please see the discussion in #222 for details.