https://github.com/python/cpython/commit/2d9d3a9f5319ce3f850341d116b63cc51869df3a
commit: 2d9d3a9f5319ce3f850341d116b63cc51869df3a
branch: main
author: Sam Gross <colesb...@gmail.com>
committer: colesbury <colesb...@gmail.com>
date: 2024-08-08T12:48:17-04:00
summary:
gh-122697: Fix free-threading memory leaks at shutdown (#122703)
We were not properly accounting for interpreter memory leaks at
shutdown and had two sources of leaks:
* Objects that use deferred reference counting and were reachable via
static types outlive the final GC. We now disable deferred reference
counting on all objects if we are calling the GC due to interpreter
shutdown.
* `_PyMem_FreeDelayed` did not properly check for interpreter shutdown
so we had some memory blocks that were enqueued to be freed, but
never actually freed.
* `_PyType_FinalizeIdPool` wasn't called at interpreter shutdown.
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2024-08-05-19-28-12.gh-issue-122697.17MvYl.rst
M Objects/obmalloc.c
M Python/gc_free_threading.c
M Python/pylifecycle.c
M Python/pystate.c
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2024-08-05-19-28-12.gh-issue-122697.17MvYl.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2024-08-05-19-28-12.gh-issue-122697.17MvYl.rst
new file mode 100644
index 00000000000000..34ee6a916bcf33
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2024-08-05-19-28-12.gh-issue-122697.17MvYl.rst
@@ -0,0 +1,2 @@
+Fixed memory leaks at interpreter shutdown in the free-threaded build, and
+also reporting of leaked memory blocks via :option:`-X showrefcount <-X>`.
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
index a6a71802ef8e01..dfeccfa4dd7658 100644
--- a/Objects/obmalloc.c
+++ b/Objects/obmalloc.c
@@ -1109,9 +1109,12 @@ free_delayed(uintptr_t ptr)
#ifndef Py_GIL_DISABLED
free_work_item(ptr);
#else
- if (_PyRuntime.stoptheworld.world_stopped) {
- // Free immediately if the world is stopped, including during
- // interpreter shutdown.
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ if (_PyInterpreterState_GetFinalizing(interp) != NULL ||
+ interp->stoptheworld.world_stopped)
+ {
+ // Free immediately during interpreter shutdown or if the world is
+ // stopped.
free_work_item(ptr);
return;
}
@@ -1474,6 +1477,8 @@
_PyInterpreterState_FinalizeAllocatedBlocks(PyInterpreterState *interp)
{
#ifdef WITH_MIMALLOC
if (_PyMem_MimallocEnabled()) {
+ Py_ssize_t leaked = _PyInterpreterState_GetAllocatedBlocks(interp);
+ interp->runtime->obmalloc.interpreter_leaks += leaked;
return;
}
#endif
diff --git a/Python/gc_free_threading.c b/Python/gc_free_threading.c
index 1e02db00649c75..543bee24652dc9 100644
--- a/Python/gc_free_threading.c
+++ b/Python/gc_free_threading.c
@@ -55,6 +55,7 @@ struct collection_state {
struct visitor_args base;
PyInterpreterState *interp;
GCState *gcstate;
+ _PyGC_Reason reason;
Py_ssize_t collected;
Py_ssize_t uncollectable;
Py_ssize_t long_lived_total;
@@ -572,6 +573,16 @@ scan_heap_visitor(const mi_heap_t *heap, const
mi_heap_area_t *area,
worklist_push(&state->unreachable, op);
}
}
+ else if (state->reason == _Py_GC_REASON_SHUTDOWN &&
+ _PyObject_HasDeferredRefcount(op))
+ {
+ // Disable deferred refcounting for reachable objects as well during
+ // interpreter shutdown. This ensures that these objects are collected
+ // immediately when their last reference is removed.
+ disable_deferred_refcounting(op);
+ merge_refcount(op, 0);
+ state->long_lived_total++;
+ }
else {
// object is reachable, restore `ob_tid`; we're done with these objects
gc_restore_tid(op);
@@ -1228,6 +1239,7 @@ gc_collect_main(PyThreadState *tstate, int generation,
_PyGC_Reason reason)
struct collection_state state = {
.interp = interp,
.gcstate = gcstate,
+ .reason = reason,
};
gc_collect_internal(interp, &state, generation);
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 6b641c0775f533..3a41c640fd9599 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -28,6 +28,7 @@
#include "pycore_sliceobject.h" // _PySlice_Fini()
#include "pycore_sysmodule.h" // _PySys_ClearAuditHooks()
#include "pycore_traceback.h" // _Py_DumpTracebackThreads()
+#include "pycore_typeid.h" // _PyType_FinalizeIdPool()
#include "pycore_typeobject.h" // _PyTypes_InitTypes()
#include "pycore_typevarobject.h" // _Py_clear_generic_types()
#include "pycore_unicodeobject.h" // _PyUnicode_InitTypes()
@@ -1832,6 +1833,9 @@ finalize_interp_types(PyInterpreterState *interp)
_PyTypes_FiniTypes(interp);
_PyTypes_Fini(interp);
+#ifdef Py_GIL_DISABLED
+ _PyType_FinalizeIdPool(interp);
+#endif
_PyCode_Fini(interp);
diff --git a/Python/pystate.c b/Python/pystate.c
index 8f4818cee00d9d..bba88b76088e71 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -20,7 +20,7 @@
#include "pycore_runtime_init.h" // _PyRuntimeState_INIT
#include "pycore_sysmodule.h" // _PySys_Audit()
#include "pycore_obmalloc.h" // _PyMem_obmalloc_state_on_heap()
-#include "pycore_typeid.h" // _PyType_FinalizeIdPool
+#include "pycore_typeid.h" // _PyType_FinalizeThreadLocalRefcounts()
/* --------------------------------------------------------------------------
CAUTION
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