osx lacks process IO counters (#1561)

* osx lacks process IO counters

* use latest osx env on travis - maybe py3.7 works now ..

* try install snappy on osx via brew

Author: oberstet

.travis.yml

@@ -19,6 +19,10 @@ addons:
       # needed for vmprof
       - libunwind-dev
 
+  homebrew:
+    packages:
+      - snappy
+
 before_install:
   - export PATH=$PATH:$HOME/.local/bin
 
@@ -73,7 +77,8 @@ matrix:
 
     # osx/cli
     - os: osx
-      language: generic
+      osx_image: xcode10.2    # Python 3.7.2 running on macOS 10.14.3
+      language: shell         # 'language: python' is an error on Travis CI macOS
       env: TOX_ENV=py37-cli
 
     # linux/examples
@@ -85,7 +90,8 @@ matrix:
 
     # osx/examples
     - os: osx
-      language: generic
+      osx_image: xcode10.2    # Python 3.7.2 running on macOS 10.14.3
+      language: shell         # 'language: python' is an error on Travis CI macOS
       env: TOX_ENV=py37-examples
 
     # linux/trial/python3
@@ -111,15 +117,18 @@ matrix:
     # osx/trial/python3
     # https://docs.travis-ci.com/user/multi-os/#Python-example-(unsupported-languages)
     - os: osx
-      language: generic
+      osx_image: xcode10.2    # Python 3.7.2 running on macOS 10.14.3
+      language: shell         # 'language: python' is an error on Travis CI macOS
       env: TOX_ENV=py37-unpinned-trial
 
     - os: osx
-      language: generic
+      osx_image: xcode10.2    # Python 3.7.2 running on macOS 10.14.3
+      language: shell         # 'language: python' is an error on Travis CI macOS
       env: TOX_ENV=py37-pinned-trial
 
     - os: osx
-      language: generic
+      osx_image: xcode10.2    # Python 3.7.2 running on macOS 10.14.3
+      language: shell         # 'language: python' is an error on Travis CI macOS
       env: TOX_ENV=py37-abtrunk-trial
 
     # https://docs.travis-ci.com/user/build-stages/matrix-expansion/

crossbar/common/monitor.py

@@ -28,6 +28,7 @@
 #
 #####################################################################################
 
+import sys
 import datetime
 import psutil
 
@@ -152,11 +153,13 @@ def __init__(self, worker_type, config):
         self._p = psutil.Process()
         self._worker_type = worker_type
 
-        try:
-            self._p.io_counters()
-            self._has_io_counters = True
-        except psutil.AccessDenied:
-            self._has_io_counters = False
+        self._has_io_counters = False
+        if not sys.platform.startswith('darwin'):
+            try:
+                self._p.io_counters()
+                self._has_io_counters = True
+            except psutil.AccessDenied:
+                pass
 
     @inlineCallbacks
     def poll(self, verbose=False):