Python 3.8 compatibility (#7754)

python/build-wheel-macos.sh

@@ -15,17 +15,21 @@ DOWNLOAD_DIR=python_downloads
 
 PY_VERSIONS=("3.5.3"
              "3.6.1"
-             "3.7.0")
+             "3.7.0"
+             "3.8.2")
 PY_INSTS=("python-3.5.3-macosx10.6.pkg"
           "python-3.6.1-macosx10.6.pkg"
-          "python-3.7.0-macosx10.6.pkg")
+          "python-3.7.0-macosx10.6.pkg"
+          "python-3.8.2-macosx10.9.pkg")
 PY_MMS=("3.5"
         "3.6"
-        "3.7")
+        "3.7"
+        "3.8")
 
 # The minimum supported numpy version is 1.14, see
 # https://issues.apache.org/jira/browse/ARROW-3141
 NUMPY_VERSIONS=("1.14.5"
+                "1.14.5"
                 "1.14.5"
                 "1.14.5")
 
@@ -76,7 +80,7 @@ for ((i=0; i<${#PY_VERSIONS[@]}; ++i)); do
     $PIP_CMD install -q setuptools_scm==3.1.0
     # Fix the numpy version because this will be the oldest numpy version we can
     # support.
-    $PIP_CMD install -q numpy==$NUMPY_VERSION cython==0.29.0
+    $PIP_CMD install -q numpy==$NUMPY_VERSION cython==0.29.15
     # Install wheel to avoid the error "invalid command 'bdist_wheel'".
     $PIP_CMD install -q wheel
     # Set the commit SHA in __init__.py.

python/build-wheel-manylinux1.sh

@@ -13,11 +13,13 @@ chmod +x /usr/bin/nproc
 
 PYTHONS=("cp35-cp35m"
          "cp36-cp36m"
-         "cp37-cp37m")
+         "cp37-cp37m"
+         "cp38-cp38")
 
 # The minimum supported numpy version is 1.14, see
 # https://issues.apache.org/jira/browse/ARROW-3141
 NUMPY_VERSIONS=("1.14.5"
+                "1.14.5"
                 "1.14.5"
                 "1.14.5")
 
@@ -55,7 +57,7 @@ for ((i=0; i<${#PYTHONS[@]}; ++i)); do
   pushd python
     # Fix the numpy version because this will be the oldest numpy version we can
     # support.
-    /opt/python/${PYTHON}/bin/pip install -q numpy==${NUMPY_VERSION} cython==0.29.0
+    /opt/python/${PYTHON}/bin/pip install -q numpy==${NUMPY_VERSION} cython==0.29.15
     # Set the commit SHA in __init__.py.
     if [ -n "$TRAVIS_COMMIT" ]; then
       sed -i.bak "s/{{RAY_COMMIT_SHA}}/$TRAVIS_COMMIT/g" ray/__init__.py && rm ray/__init__.py.bak

python/ray/cloudpickle/cloudpickle_fast.py

@@ -417,7 +417,7 @@ def _numpy_frombuffer(buffer, dtype, shape, order):
     array = _frombuffer(buffer, dtype, shape, order)
     # Unfortunately, numpy does not follow the standard, so we still
     # have to set the readonly flag for it here.
-    array.setflags(write=not buffer.readonly)
+    array.setflags(write=isinstance(buffer, bytearray) or not buffer.readonly)
     return array
 
 

python/setup.py

@@ -191,7 +191,7 @@ setup(
     # The BinaryDistribution argument triggers build_ext.
     distclass=BinaryDistribution,
     install_requires=requires,
-    setup_requires=["cython >= 0.29"],
+    setup_requires=["cython >= 0.29.14"],
     extras_require=extras,
     entry_points={
         "console_scripts": [