fix: resolve RAM default pid at init time

codecarbon/external/ram.py

@@ -1,4 +1,5 @@
 import math
+import os
 import re
 import subprocess
 from dataclasses import dataclass
@@ -34,7 +35,7 @@ class RAM(BaseHardware):
 
     def __init__(
         self,
-        pid: int = psutil.Process().pid,
+        pid: Optional[int] = None,
         children: bool = True,
         tracking_mode: str = "machine",
         force_ram_power: Optional[int] = None,
@@ -46,7 +47,7 @@ def __init__(
 
         Args:
             pid (int, optional): Process id (with respect to which we'll look for
-                                 children). Defaults to psutil.Process().pid.
+                                 children). Defaults to the current process id.
             children (int, optional): Look for children of the process when computing
                                       total RAM used. Defaults to True.
             tracking_mode (str, optional): Whether to track "machine" or "process" RAM.
@@ -55,7 +56,7 @@ def __init__(
                                            this value is used instead of estimating RAM power.
                                            Defaults to None.
         """
-        self._pid = pid
+        self._pid = os.getpid() if pid is None else pid
         self._children = children
         self._tracking_mode = tracking_mode
         self._force_ram_power = force_ram_power

tests/test_ram.py

@@ -1,9 +1,11 @@
+import os
 import subprocess
 import unittest
 from textwrap import dedent
 from unittest import mock
 
 import numpy as np
+import pytest
 
 from codecarbon.external.ram import RAM, RAM_SLOT_POWER_X86
 
@@ -437,3 +439,23 @@ def test_force_ram_power(self):
             ram_power = ram.total_power()
             # Verify the calculation method was not called
             mock_calc.assert_not_called()
+
+    @pytest.mark.skipif(not hasattr(os, "fork"), reason="requires os.fork")
+    def test_default_pid_is_resolved_in_forked_child(self):
+        read_fd, write_fd = os.pipe()
+        pid = os.fork()
+        if pid == 0:
+            # Child: the module is already imported, so a default argument
+            # evaluated at import time would still hold the parent's pid.
+            try:
+                os.close(read_fd)
+                ram = RAM(tracking_mode="process")
+                os.write(write_fd, str(ram._pid).encode())
+                os.close(write_fd)
+            finally:
+                os._exit(0)
+        os.close(write_fd)
+        with os.fdopen(read_fd) as f:
+            child_ram_pid = int(f.read())
+        os.waitpid(pid, 0)
+        self.assertEqual(child_ram_pid, pid)