Fix get_child_process_ids parsing issue (#5416)

Co-authored-by: pintaoz <pintaoz@amazon.com>

Author: pintaoz-aws

sagemaker-core/src/sagemaker/core/local/utils.py

@@ -137,7 +137,11 @@ def get_child_process_ids(pid):
     Returns:
         (List[int]): Child process ids
     """
-    cmd = f"pgrep -P {pid}".split()
+    if not str(pid).isdigit():
+        raise ValueError("Invalid PID")
+    
+    cmd = ["pgrep", "-P", str(pid)]
+    
     process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     output, err = process.communicate()
     if err:

sagemaker-core/tests/unit/local/test_local_utils.py

@@ -103,21 +103,24 @@ def test_recursive_copy(copy_tree, m_os_path):
 @patch("sagemaker.core.local.utils.os")
 @patch("sagemaker.core.local.utils.get_child_process_ids")
 def test_kill_child_processes(m_get_child_process_ids, m_os):
-    m_get_child_process_ids.return_value = ["child_pids"]
-    kill_child_processes("pid")
-    m_os.kill.assert_called_with("child_pids", 15)
+    m_get_child_process_ids.return_value = ["345"]
+    kill_child_processes("123")
+    m_os.kill.assert_called_with("345", 15)
 
 
 @patch("sagemaker.core.local.utils.subprocess")
 def test_get_child_process_ids(m_subprocess):
-    cmd = "pgrep -P pid".split()
+    cmd = "pgrep -P 123".split()
     process_mock = Mock()
     attrs = {"communicate.return_value": (b"\n", False), "returncode": 0}
     process_mock.configure_mock(**attrs)
     m_subprocess.Popen.return_value = process_mock
-    get_child_process_ids("pid")
+    get_child_process_ids("123")
     m_subprocess.Popen.assert_called_with(cmd, stdout=m_subprocess.PIPE, stderr=m_subprocess.PIPE)
 
+def test_get_child_process_ids_exception():
+    with pytest.raises(ValueError, match="Invalid PID"):
+        get_child_process_ids("abc")
 
 @patch("sagemaker.core.local.utils.subprocess")
 def test_get_docker_host(m_subprocess):