Require process creation time.

testing/devpi.py

@@ -18,7 +18,7 @@
 from pex.common import safe_open, safe_rmtree
 from pex.interpreter import PythonInterpreter
 from pex.interpreter_constraints import InterpreterConstraint
-from pex.typing import TYPE_CHECKING
+from pex.typing import TYPE_CHECKING, cast
 from pex.venv.virtualenv import InvalidVirtualenvError, Virtualenv
 from testing import PEX_TEST_DEV_ROOT
 
@@ -46,7 +46,7 @@ def load(cls):
         try:
             with open(cls._PATH) as fp:
                 data = json.load(fp)
-            return cls(url=data["url"], pid=data["pid"], create_time=data.get("create_time"))
+            return cls(url=data["url"], pid=data["pid"], create_time=data["create_time"])
         except (OSError, IOError, ValueError, KeyError) as e:
             logger.warning(
                 "Failed to load devpi-server pid file from {path}: {err}".format(
@@ -71,6 +71,14 @@ def _read_base_url(
                             return match.group("url")
         return None
 
+    @staticmethod
+    def _get_process_creation_time(pid):
+        # type: (int) -> Optional[float]
+        try:
+            return cast(float, psutil.Process(pid).create_time())
+        except psutil.Error:
+            return None
+
     @classmethod
     def record(
         cls,
@@ -83,9 +91,8 @@ def record(
         if not base_url:
             return None
 
-        try:
-            create_time = psutil.Process(pid).create_time()
-        except psutil.Error:
+        create_time = cls._get_process_creation_time(pid)
+        if create_time is None:
             return None
 
         url = "{base_url}/root/pypi/+simple/".format(base_url=base_url)
@@ -95,15 +102,11 @@ def record(
 
     url = attr.ib()  # type: str
     pid = attr.ib()  # type: int
-    create_time = attr.ib()  # type: Optional[float]
+    create_time = attr.ib()  # type: float
 
     def alive(self):
         # type: () -> bool
-        try:
-            process = psutil.Process(self.pid)
-            return self.create_time is None or self.create_time == process.create_time()
-        except psutil.NoSuchProcess:
-            return False
+        return self.create_time == self._get_process_creation_time(self.pid)
 
     def kill(self):
         # type: () -> None