From 069fb0cffcee780267c6151838519883f3be084d Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Thu, 20 Feb 2025 20:16:12 -0800
Subject: [PATCH 01/16] fix resource tracker leak

---
 Lib/multiprocessing/resource_tracker.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 90e036ae905afa..23213f76004fce 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -212,6 +212,9 @@ def _send(self, cmd, name, rtype):
         assert nbytes == len(msg), "nbytes {0:n} but len(msg) {1:n}".format(
             nbytes, len(msg))
 
+    def __del__(self):
+        self._stop()
+
 
 _resource_tracker = ResourceTracker()
 ensure_running = _resource_tracker.ensure_running

From 5e338289c119c719ab07fb9e8df54933e755d6e8 Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Thu, 20 Feb 2025 22:20:27 -0800
Subject: [PATCH 02/16] try block

---
 Lib/multiprocessing/resource_tracker.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 23213f76004fce..38879fbb9cd5ce 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -213,7 +213,10 @@ def _send(self, cmd, name, rtype):
             nbytes, len(msg))
 
     def __del__(self):
-        self._stop()
+        try:
+            self._stop()
+        except:
+            pass
 
 
 _resource_tracker = ResourceTracker()

From 0586696d17279c172fc28e07ae34f7b843469e25 Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Fri, 21 Feb 2025 14:38:11 -0800
Subject: [PATCH 03/16] add comment to resource tracker __del__

---
 Lib/multiprocessing/resource_tracker.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 38879fbb9cd5ce..7316cc9bc135bd 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -213,6 +213,9 @@ def _send(self, cmd, name, rtype):
             nbytes, len(msg))
 
     def __del__(self):
+        # making sure child processess are cleaned before ResourceTracker
+        # gets destructed.
+        # see https://github.com/python/cpython/issues/88887
         try:
             self._stop()
         except:

From eeef2e4a9ab8d31578fc3840128f6a7668ba5a63 Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Fri, 21 Feb 2025 14:48:02 -0800
Subject: [PATCH 04/16] blurb add

---
 .../2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst                | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst
new file mode 100644
index 00000000000000..a178d045e0ed28
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst
@@ -0,0 +1 @@
+Fixing multiprocessing Resource Tracker process leaking

From 933f70c8199b049196742ed0507d551f9608d69c Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Mon, 24 Feb 2025 12:12:07 -0800
Subject: [PATCH 05/16] catch specific exceptions

---
 Lib/multiprocessing/resource_tracker.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 7316cc9bc135bd..a4a84d80992c48 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -218,7 +218,7 @@ def __del__(self):
         # see https://github.com/python/cpython/issues/88887
         try:
             self._stop()
-        except:
+        except (OSError, TypeError, AttributeError) as e:
             pass
 
 

From 799ee32d79eabcc9597480cc54edfadd0026fd8e Mon Sep 17 00:00:00 2001
From: luccabb <32229669+luccabb@users.noreply.github.com>
Date: Mon, 24 Feb 2025 12:58:14 -0800
Subject: [PATCH 06/16] Update Lib/multiprocessing/resource_tracker.py

Co-authored-by: Victor Stinner <vstinner@python.org>
---
 Lib/multiprocessing/resource_tracker.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index a4a84d80992c48..1c7c15a73da566 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -218,7 +218,7 @@ def __del__(self):
         # see https://github.com/python/cpython/issues/88887
         try:
             self._stop()
-        except (OSError, TypeError, AttributeError) as e:
+        except (OSError, TypeError, AttributeError):
             pass
 
 

From 8e43a8393305b49915f150f1593273fa220c6e15 Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Thu, 6 Mar 2025 11:53:15 -0800
Subject: [PATCH 07/16] fixing _stop for None pids

---
 Lib/multiprocessing/resource_tracker.py | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index a4a84d80992c48..946405f48ec555 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -75,8 +75,16 @@ def _reentrant_call_error(self):
         raise ReentrantCallError(
             "Reentrant call into the multiprocessing resource tracker")
 
+    def __del__(self):
+        # making sure child processess are cleaned before ResourceTracker
+        # gets destructed.
+        # see https://github.com/python/cpython/issues/88887
+        self._stop()
+
     def _stop(self):
         with self._lock:
+            if self._pid is None:
+                return
             # This should not happen (_stop() isn't called by a finalizer)
             # but we check for it anyway.
             if self._lock._recursion_count() > 1:
@@ -191,7 +199,7 @@ def unregister(self, name, rtype):
         '''Unregister name of resource with resource tracker.'''
         self._send('UNREGISTER', name, rtype)
 
-    def _send(self, cmd, name, rtype):
+    def _send(self, cmd, name, rtype)::77
         try:
             self.ensure_running()
         except ReentrantCallError:
@@ -212,16 +220,6 @@ def _send(self, cmd, name, rtype):
         assert nbytes == len(msg), "nbytes {0:n} but len(msg) {1:n}".format(
             nbytes, len(msg))
 
-    def __del__(self):
-        # making sure child processess are cleaned before ResourceTracker
-        # gets destructed.
-        # see https://github.com/python/cpython/issues/88887
-        try:
-            self._stop()
-        except (OSError, TypeError, AttributeError) as e:
-            pass
-
-
 _resource_tracker = ResourceTracker()
 ensure_running = _resource_tracker.ensure_running
 register = _resource_tracker.register

From 805ad1d76557cc24142caef94e3f9fbec38db67e Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Thu, 6 Mar 2025 12:01:47 -0800
Subject: [PATCH 08/16] remove :77 typo

---
 Lib/multiprocessing/resource_tracker.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 946405f48ec555..91b30cfd998573 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -199,7 +199,7 @@ def unregister(self, name, rtype):
         '''Unregister name of resource with resource tracker.'''
         self._send('UNREGISTER', name, rtype)
 
-    def _send(self, cmd, name, rtype)::77
+    def _send(self, cmd, name, rtype):
         try:
             self.ensure_running()
         except ReentrantCallError:

From 5d6c9b3dabf74adfdcfd884ef5f2faa72dade207 Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Thu, 6 Mar 2025 12:02:46 -0800
Subject: [PATCH 09/16] add extra line back

---
 Lib/multiprocessing/resource_tracker.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 91b30cfd998573..d6bf49527a6290 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -220,6 +220,7 @@ def _send(self, cmd, name, rtype):
         assert nbytes == len(msg), "nbytes {0:n} but len(msg) {1:n}".format(
             nbytes, len(msg))
 
+
 _resource_tracker = ResourceTracker()
 ensure_running = _resource_tracker.ensure_running
 register = _resource_tracker.register

From c8e2704c2572f6e52cb04769b20b476321a9daa3 Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Thu, 6 Mar 2025 15:42:01 -0800
Subject: [PATCH 10/16] catch AttributeError only and return early from _stop
 if _pid is None

---
 Lib/multiprocessing/resource_tracker.py | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index d6bf49527a6290..b4574bf897a9a2 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -79,12 +79,18 @@ def __del__(self):
         # making sure child processess are cleaned before ResourceTracker
         # gets destructed.
         # see https://github.com/python/cpython/issues/88887
-        self._stop()
+        try:
+            self._stop()
+        except AttributeError:
+            # AttributeError is likely caused by module teardown
+            # > __del__() can be executed during interpreter shutdown. As a 
+            # > consequence, the global variables it needs to access (including 
+            # > other modules) may already have been deleted or set to None.
+            # see https://docs.python.org/3/reference/datamodel.html#object.__del__
+            pass
 
     def _stop(self):
         with self._lock:
-            if self._pid is None:
-                return
             # This should not happen (_stop() isn't called by a finalizer)
             # but we check for it anyway.
             if self._lock._recursion_count() > 1:
@@ -92,6 +98,8 @@ def _stop(self):
             if self._fd is None:
                 # not running
                 return
+            if self._pid is None:
+                return
 
             # closing the "alive" file descriptor stops main()
             os.close(self._fd)

From 9fd5872c8f09718fe0c6171fd5d70b207982732e Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Thu, 6 Mar 2025 15:47:50 -0800
Subject: [PATCH 11/16] fix lint

---
 Lib/multiprocessing/resource_tracker.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index b4574bf897a9a2..eb5c2ea997b575 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -83,8 +83,8 @@ def __del__(self):
             self._stop()
         except AttributeError:
             # AttributeError is likely caused by module teardown
-            # > __del__() can be executed during interpreter shutdown. As a 
-            # > consequence, the global variables it needs to access (including 
+            # > __del__() can be executed during interpreter shutdown. As a
+            # > consequence, the global variables it needs to access (including
             # > other modules) may already have been deleted or set to None.
             # see https://docs.python.org/3/reference/datamodel.html#object.__del__
             pass

From aaa8378f4da2c5a6059e761e6097adec67e66c68 Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Fri, 7 Mar 2025 10:55:03 -0800
Subject: [PATCH 12/16] injecting os methods on _stop

---
 Lib/multiprocessing/resource_tracker.py | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index eb5c2ea997b575..feacf7a329269a 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -79,17 +79,9 @@ def __del__(self):
         # making sure child processess are cleaned before ResourceTracker
         # gets destructed.
         # see https://github.com/python/cpython/issues/88887
-        try:
-            self._stop()
-        except AttributeError:
-            # AttributeError is likely caused by module teardown
-            # > __del__() can be executed during interpreter shutdown. As a
-            # > consequence, the global variables it needs to access (including
-            # > other modules) may already have been deleted or set to None.
-            # see https://docs.python.org/3/reference/datamodel.html#object.__del__
-            pass
+        self._stop()
 
-    def _stop(self):
+    def _stop(self, close=os.close, waitpid=os.waitpid, waitstatus_to_exitcode=os.waitstatus_to_exitcode):
         with self._lock:
             # This should not happen (_stop() isn't called by a finalizer)
             # but we check for it anyway.
@@ -102,15 +94,15 @@ def _stop(self):
                 return
 
             # closing the "alive" file descriptor stops main()
-            os.close(self._fd)
+            close(self._fd)
             self._fd = None
 
-            _, status = os.waitpid(self._pid, 0)
+            _, status = waitpid(self._pid, 0)
 
             self._pid = None
 
             try:
-                self._exitcode = os.waitstatus_to_exitcode(status)
+                self._exitcode = waitstatus_to_exitcode(status)
             except ValueError:
                 # os.waitstatus_to_exitcode may raise an exception for invalid values
                 self._exitcode = None

From dc2d578508d320496c7c26e459e6f06e39cd51df Mon Sep 17 00:00:00 2001
From: "Gregory P. Smith" <greg@krypto.org>
Date: Fri, 7 Mar 2025 13:29:02 -0800
Subject: [PATCH 13/16] Update Lib/multiprocessing/resource_tracker.py comment

---
 Lib/multiprocessing/resource_tracker.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index feacf7a329269a..125a6190d2be16 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -83,8 +83,8 @@ def __del__(self):
 
     def _stop(self, close=os.close, waitpid=os.waitpid, waitstatus_to_exitcode=os.waitstatus_to_exitcode):
         with self._lock:
-            # This should not happen (_stop() isn't called by a finalizer)
-            # but we check for it anyway.
+            # This shouldn't happen (it might when called by a finalizer)
+            # so we check for it anyway.
             if self._lock._recursion_count() > 1:
                 return self._reentrant_call_error()
             if self._fd is None:

From 98473429b989c347ff7b7ee840d90b00274941dd Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Sat, 8 Mar 2025 22:53:11 -0800
Subject: [PATCH 14/16] non blocking acquire for __del__

---
 Lib/multiprocessing/resource_tracker.py | 54 ++++++++++++++-----------
 1 file changed, 31 insertions(+), 23 deletions(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index feacf7a329269a..3b635d58ccb546 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -79,33 +79,41 @@ def __del__(self):
         # making sure child processess are cleaned before ResourceTracker
         # gets destructed.
         # see https://github.com/python/cpython/issues/88887
-        self._stop()
+        self._stop(use_blocking_lock=False)
 
-    def _stop(self, close=os.close, waitpid=os.waitpid, waitstatus_to_exitcode=os.waitstatus_to_exitcode):
-        with self._lock:
-            # This should not happen (_stop() isn't called by a finalizer)
-            # but we check for it anyway.
-            if self._lock._recursion_count() > 1:
-                return self._reentrant_call_error()
-            if self._fd is None:
-                # not running
-                return
-            if self._pid is None:
-                return
-
-            # closing the "alive" file descriptor stops main()
-            close(self._fd)
-            self._fd = None
+    def _stop(self, use_blocking_lock=True):
+        if use_blocking_lock:
+            with self._lock:
+                self._cleanup()
+        else:
+            self._lock.acquire(blocking=False)
+            self._cleanup()
+            self._lock.release()
+
+    def _cleanup(self, close=os.close, waitpid=os.waitpid, waitstatus_to_exitcode=os.waitstatus_to_exitcode):
+        # This should not happen (_stop() isn't called by a finalizer)
+        # but we check for it anyway.
+        if self._lock._recursion_count() > 1:
+            return self._reentrant_call_error()
+        if self._fd is None:
+            # not running
+            return
+        if self._pid is None:
+            return
+
+        # closing the "alive" file descriptor stops main()
+        close(self._fd)
+        self._fd = None
 
-            _, status = waitpid(self._pid, 0)
+        _, status = waitpid(self._pid, 0)
 
-            self._pid = None
+        self._pid = None
 
-            try:
-                self._exitcode = waitstatus_to_exitcode(status)
-            except ValueError:
-                # os.waitstatus_to_exitcode may raise an exception for invalid values
-                self._exitcode = None
+        try:
+            self._exitcode = waitstatus_to_exitcode(status)
+        except ValueError:
+            # os.waitstatus_to_exitcode may raise an exception for invalid values
+            self._exitcode = None
 
     def getfd(self):
         self.ensure_running()

From d497deecf19f5c56ed629eec0bbf21534449674d Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Mon, 10 Mar 2025 09:57:40 -0700
Subject: [PATCH 15/16] release only if acquired

---
 Lib/multiprocessing/resource_tracker.py | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 8c6dd0052ad742..54f95f5cc0bbdd 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -84,13 +84,19 @@ def __del__(self):
     def _stop(self, use_blocking_lock=True):
         if use_blocking_lock:
             with self._lock:
-                self._cleanup()
+                self._stop_unlocked()
         else:
-            self._lock.acquire(blocking=False)
-            self._cleanup()
-            self._lock.release()
-
-    def _cleanup(self, close=os.close, waitpid=os.waitpid, waitstatus_to_exitcode=os.waitstatus_to_exitcode):
+            acquired = self._lock.acquire(blocking=False)
+            self._stop_unlocked()
+            if acquired:
+                self._lock.release()
+
+    def _stop_unlocked(
+        self,
+        close=os.close,
+        waitpid=os.waitpid,
+        waitstatus_to_exitcode=os.waitstatus_to_exitcode,
+    ):
         # This shouldn't happen (it might when called by a finalizer)
         # so we check for it anyway.
         if self._lock._recursion_count() > 1:

From ba424061c93cb318964f1c4420a8fc720b5329de Mon Sep 17 00:00:00 2001
From: Lucca Bertoncini <luccab@fb.com>
Date: Wed, 19 Mar 2025 11:29:44 -0700
Subject: [PATCH 16/16] always release + changelog

---
 Lib/multiprocessing/resource_tracker.py              | 12 +++++++-----
 .../2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst    |  2 +-
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 54f95f5cc0bbdd..05633ac21a259c 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -84,14 +84,16 @@ def __del__(self):
     def _stop(self, use_blocking_lock=True):
         if use_blocking_lock:
             with self._lock:
-                self._stop_unlocked()
+                self._stop_locked()
         else:
             acquired = self._lock.acquire(blocking=False)
-            self._stop_unlocked()
-            if acquired:
-                self._lock.release()
+            try:
+                self._stop_locked()
+            finally:
+                if acquired:
+                    self._lock.release()
 
-    def _stop_unlocked(
+    def _stop_locked(
         self,
         close=os.close,
         waitpid=os.waitpid,
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst
index a178d045e0ed28..1a6c9483e2a35e 100644
--- a/Misc/NEWS.d/next/Core_and_Builtins/2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-02-21-14-47-46.gh-issue-88887.V3U0CV.rst
@@ -1 +1 @@
-Fixing multiprocessing Resource Tracker process leaking
+Fixing multiprocessing Resource Tracker process leaking, usually observed when running Python as PID 1.