[BugFix] Enforce C locale for CPU binding subprocess parsing (#8261)

### What this PR does / why we need it?
This PR backports the CPU binding locale normalization fix from #7274 to
`releases/v0.18.0`, including the follow-up review fixes already applied
on `main`.

The change forces `LC_ALL`, `LANG`, and `LC_MESSAGES` to `C` before
spawning subprocesses in `vllm_ascend.cpu_binding.execute_command()`, so
parser-dependent command output stays stable on localized systems. It
also handles `subprocess.TimeoutExpired` by killing the child process
before collecting output, and updates the existing unit tests to keep
command-argument coverage while adding timeout-path coverage.

Fixes #6992

### Does this PR introduce _any_ user-facing change?
Yes.

Users running CPU binding on non-English OS environments should now get
consistent English subprocess output for parser-dependent commands,
avoiding failures caused by inherited locale settings.

### How was this patch tested?
- Updated the existing unit tests in
`tests/ut/device_allocator/test_cpu_binding.py` to assert the locale
environment, retain command argument coverage, and cover the timeout
cleanup path.
- Attempted to run targeted pytest cases locally, but the pytest
invocation did not complete normally in this environment, so I could not
record a clean passing run here.

Attribution:
- Co-authored-by: stdjhs <1601599324@qq.com>
- Signed-off-by: chenchuw886 <chenchuw@huawei.com>

Signed-off-by: chenchuw886 <chenchuw@huawei.com>
Co-authored-by: chenchuw886 <chenchuw@huawei.com>
Co-authored-by: stdjhs <1601599324@qq.com>

tests/ut/device_allocator/test_cpu_binding.py

@@ -1,12 +1,50 @@
+import subprocess
 import unittest
-from unittest.mock import mock_open, patch
+from unittest.mock import MagicMock, mock_open, patch
 
+import vllm_ascend.cpu_binding as cpu_binding_module
 from vllm_ascend.cpu_binding import CpuAlloc, DeviceInfo, bind_cpus, is_arm_cpu
 from vllm_ascend.utils import AscendDeviceType
 
 
 class TestDeviceInfo(unittest.TestCase):
+    @patch('vllm_ascend.cpu_binding.subprocess.Popen')
+    def test_execute_command(self, mock_popen):
+        process = MagicMock()
+        process.communicate.return_value = (b'command-output', b'')
+        process.returncode = 7
+        mock_popen.return_value.__enter__.return_value = process
 
+        output, return_code = cpu_binding_module.execute_command(['dummy', 'cmd'])
+
+        self.assertEqual(output, 'command-output')
+        self.assertEqual(return_code, 7)
+        mock_popen.assert_called_once()
+        args, kwargs = mock_popen.call_args
+        self.assertEqual(args[0], ['dummy', 'cmd'])
+        self.assertEqual(kwargs["shell"], False)
+        self.assertEqual(kwargs["stdout"], subprocess.PIPE)
+        self.assertEqual(kwargs["stderr"], subprocess.PIPE)
+        self.assertEqual(kwargs["env"]["LC_ALL"], "C")
+        self.assertEqual(kwargs["env"]["LANG"], "C")
+        self.assertEqual(kwargs["env"]["LC_MESSAGES"], "C")
+
+    @patch('vllm_ascend.cpu_binding.subprocess.Popen')
+    def test_execute_command_kills_timed_out_process(self, mock_popen):
+        process = MagicMock()
+        process.communicate.side_effect = [
+            subprocess.TimeoutExpired(cmd=['dummy', 'cmd'], timeout=1000),
+            (b'command-output', b''),
+        ]
+        process.returncode = -9
+        mock_popen.return_value.__enter__.return_value = process
+
+        output, return_code = cpu_binding_module.execute_command(['dummy', 'cmd'])
+
+        self.assertEqual(output, 'command-output')
+        self.assertEqual(return_code, -9)
+        process.kill.assert_called_once_with()
+        self.assertEqual(process.communicate.call_count, 2)
     @patch('vllm_ascend.cpu_binding.execute_command')
     def setUp(self, mock_execute_command):
         mock_execute_command.side_effect = [

vllm_ascend/cpu_binding.py

@@ -37,8 +37,17 @@ def is_arm_cpu() -> bool:
 
 
 def execute_command(cmd: list[str]) -> tuple[str, int]:
-    with subprocess.Popen(cmd, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE) as p:
+    # Force a C locale so subprocess output remains parseable on localized OSes.
+    env = os.environ.copy()
+    env["LC_ALL"] = "C"
+    env["LANG"] = "C"
+    env["LC_MESSAGES"] = "C"
+    with subprocess.Popen(cmd, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, env=env) as p:
+        try:
             out, _ = p.communicate(timeout=1000)
+        except subprocess.TimeoutExpired:
+            p.kill()
+            out, _ = p.communicate()
     return out.decode(), p.returncode