Ignore prlimit argument on Windows

The built in 'resource' module is used in order to apply process
resource limits. This is not available on Windows.

For the moment, we'll ignore this argument and log a warning
message. In the future, we may provide a portable implementation
for this feature.

Change-Id: I6a82916eb68fbf8737b45a65f71cae1f835d12d1
Closes-Bug: #1627766

oslo_concurrency/processutils.py

@@ -327,11 +327,16 @@ def execute(*cmd, **kwargs):
     cmd = [str(c) for c in cmd]
 
     if prlimit:
-        args = [sys.executable, '-m', 'oslo_concurrency.prlimit']
-        args.extend(prlimit.prlimit_args())
-        args.append('--')
-        args.extend(cmd)
-        cmd = args
+        if os.name == 'nt':
+            LOG.log(loglevel,
+                    _('Process resource limits are ignored as '
+                      'this feature is not supported on Windows.'))
+        else:
+            args = [sys.executable, '-m', 'oslo_concurrency.prlimit']
+            args.extend(prlimit.prlimit_args())
+            args.append('--')
+            args.extend(cmd)
+            cmd = args
 
     sanitized_cmd = strutils.mask_password(' '.join(cmd))
 

oslo_concurrency/tests/unit/test_processutils.py

@@ -895,3 +895,25 @@ class PrlimitTestCase(test_base.BaseTestCase):
             self.assertIn(expected, exc.stderr)
         else:
             self.fail("ProcessExecutionError not raised")
+
+    @mock.patch.object(os, 'name', 'nt')
+    @mock.patch.object(processutils.subprocess, "Popen")
+    def test_prlimit_windows(self, mock_popen):
+        # We want to ensure that process resource limits are
+        # ignored on Windows, in which case this feature is not
+        # supported. We'll just check the command passed to Popen,
+        # which is expected to be unaltered.
+        prlimit = self.limit_address_space()
+        mock_popen.return_value.communicate.return_value = None
+
+        processutils.execute(
+            *self.SIMPLE_PROGRAM,
+            prlimit=prlimit,
+            check_exit_code=False)
+
+        mock_popen.assert_called_once_with(
+            self.SIMPLE_PROGRAM,
+            stdin=mock.ANY, stdout=mock.ANY,
+            stderr=mock.ANY, close_fds=mock.ANY,
+            preexec_fn=mock.ANY, shell=mock.ANY,
+            cwd=mock.ANY, env=mock.ANY)