Testing spawning for windows

.github/workflows/python-package.yml

@@ -63,14 +63,14 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - uses: actions/setup-python@v3
+      - uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
 
       - name: Install cibuildwheel
         run: python -m pip install cibuildwheel==2.17.0
 
-      - name: Build wheels
+      - name: Build wheels and run pytest
         run: python -m cibuildwheel --output-dir wheelhouse
         env:
           CIBW_BEFORE_BUILD: "pip install numpy"

mc3/chain.py

@@ -1,6 +1,7 @@
 # Copyright (c) 2015-2023 Patricio Cubillos and contributors.
 # mc3 is open-source software under the MIT license (see LICENSE).
 
+import platform
 import sys
 import warnings
 import random
@@ -13,9 +14,13 @@
 
 # Ingnore RuntimeWarnings:
 warnings.simplefilter("ignore", RuntimeWarning)
+if platform.system() == 'Windows':
+    multiprocess_context = mp.get_context('spawn')
+else:
+    multiprocess_context = mp.get_context('fork')
 
 
-class Chain(mp.get_context('fork').Process):
+class Chain(multiprocess_context.Process):
   """
   Background process.  This guy evaluates the model and calculates chisq.
   """

mc3/mcmc_driver.py

@@ -5,6 +5,7 @@
     'mcmc',
 ]
 
+import platform
 import time
 import ctypes
 import multiprocessing as mpr
@@ -206,11 +207,16 @@ def mcmc(
     ncpp[0:nchains % ncpu] += 1
 
     # Launch Chains:
-    mp_context = mpr.get_context('fork')
+    if platform.system() == 'Windows':
+        multiprocess_context = mp.get_context('spawn')
+    else:
+        multiprocess_context = mp.get_context('fork')
+
+    #mp_context = mpr.get_context('fork')
     pipes  = []
     chains = []
     for i in range(ncpu):
-        p = mp_context.Pipe()
+        p = multiprocess_context.Pipe()
         pipes.append(p[0])
         chains.append(
             ch.Chain(func, indparams, indparams_dict, p[1], data, uncert,