From 242ddf4aa33c6e1e89c5fa734f8040c4c316c501 Mon Sep 17 00:00:00 2001
From: maurycy <5383+maurycy@users.noreply.github.com>
Date: Sat, 6 Dec 2025 01:18:24 +0100
Subject: [PATCH 1/2] jit: lazy executor flush while the world stopped

---
 Python/optimizer.c | 13 ++++++++++++-
 Python/pystate.c   | 12 ++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/Python/optimizer.c b/Python/optimizer.c
index 9db894f0bf054a..647c634bdac2a5 100644
--- a/Python/optimizer.c
+++ b/Python/optimizer.c
@@ -293,6 +293,17 @@ _Py_ClearExecutorDeletionList(PyInterpreterState *interp)
     interp->executor_deletion_list_remaining_capacity = EXECUTOR_DELETE_LIST_MAX;
 }
 
+static inline int
+can_clear_executor_deletion_list(PyInterpreterState *interp)
+{
+#ifdef Py_GIL_DISABLED
+    if (_PyRuntime.stoptheworld.world_stopped || interp->stoptheworld.world_stopped) {
+        return 0;
+    }
+#endif
+    return 1;
+}
+
 static void
 add_to_pending_deletion_list(_PyExecutorObject *self)
 {
@@ -302,7 +313,7 @@ add_to_pending_deletion_list(_PyExecutorObject *self)
     if (interp->executor_deletion_list_remaining_capacity > 0) {
         interp->executor_deletion_list_remaining_capacity--;
     }
-    else {
+    else if (can_clear_executor_deletion_list(interp)) {
         _Py_ClearExecutorDeletionList(interp);
     }
 }
diff --git a/Python/pystate.c b/Python/pystate.c
index c12a1418e74309..c0e02aeec51e12 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -2358,6 +2358,18 @@ start_the_world(struct _stoptheworld_state *stw)
     _PyRuntimeState *runtime = &_PyRuntime;
     assert(PyMutex_IsLocked(&stw->mutex));
 
+#ifdef _Py_TIER2
+    if (stw->is_global) {
+        _Py_FOR_EACH_STW_INTERP(stw, interp) {
+            _Py_ClearExecutorDeletionList(interp);
+        }
+    }
+    else {
+        PyInterpreterState *interp = _Py_CONTAINER_OF(stw, PyInterpreterState, stoptheworld);
+        _Py_ClearExecutorDeletionList(interp);
+    }
+#endif
+
     HEAD_LOCK(runtime);
     stw->requested = 0;
     stw->world_stopped = 0;

From 48f6b6b1e90eced7a0e2d7974f4c9009100b3444 Mon Sep 17 00:00:00 2001
From: maurycy <5383+maurycy@users.noreply.github.com>
Date: Sat, 6 Dec 2025 01:25:38 +0100
Subject: [PATCH 2/2] blurb

---
 .../2025-12-06-01-25-04.gh-issue-141658.g039M-.rst              | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2025-12-06-01-25-04.gh-issue-141658.g039M-.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-12-06-01-25-04.gh-issue-141658.g039M-.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-06-01-25-04.gh-issue-141658.g039M-.rst
new file mode 100644
index 00000000000000..d8771c817d1106
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-06-01-25-04.gh-issue-141658.g039M-.rst
@@ -0,0 +1,2 @@
+Fix a deadlock where JIT executor drain could run under the rutime lock when
+invalidations overflow the pending list.