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bpo-35053: Enhance tracemalloc to trace free lists (GH-10063)

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tracemalloc now tries to update the traceback when an object is
reused from a "free list" (optimization for faster object creation,
used by the builtin list type for example).

Changes:

* Add _PyTraceMalloc_NewReference() function which tries to update
  the Python traceback of a Python object.
* _Py_NewReference() now calls _PyTraceMalloc_NewReference().
* Add an unit test.
This commit is contained in:
Victor Stinner 2018-10-25 13:31:16 +02:00 committed by GitHub
parent d7c3e5f0e8
commit 9e00e80e21
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
7 changed files with 157 additions and 51 deletions
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3
Include/object.h
View file

@ -776,6 +776,9 @@ PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *, int force);
* inline.
*/
#define _Py_NewReference(op) ( \
(_Py_tracemalloc_config.tracing \
? _PyTraceMalloc_NewReference(op) \
: 0), \
_Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA \
_Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \
Py_REFCNT(op) = 1)

38
Include/pymem.h
View file

@ -36,6 +36,10 @@ PyAPI_FUNC(int) PyTraceMalloc_Track(
uintptr_t ptr,
size_t size);
/* Update the Python traceback of an object.
This function can be used when a memory block is reused from a free list. */
PyAPI_FUNC(int) _PyTraceMalloc_NewReference(PyObject *op);
/* Untrack an allocated memory block in the tracemalloc module.
Do nothing if the block was not tracked.
@ -239,6 +243,40 @@ PyAPI_FUNC(int) _PyMem_SetDefaultAllocator(
PyMemAllocatorEx *old_alloc);
#endif
/* bpo-35053: expose _Py_tracemalloc_config for performance:
_Py_NewReference() needs an efficient check to test if tracemalloc is
tracing. */
struct _PyTraceMalloc_Config {
/* Module initialized?
Variable protected by the GIL */
enum {
TRACEMALLOC_NOT_INITIALIZED,
TRACEMALLOC_INITIALIZED,
TRACEMALLOC_FINALIZED
} initialized;
/* Is tracemalloc tracing memory allocations?
Variable protected by the GIL */
int tracing;
/* limit of the number of frames in a traceback, 1 by default.
Variable protected by the GIL. */
int max_nframe;
/* use domain in trace key?
Variable protected by the GIL. */
int use_domain;
};
PyAPI_DATA(struct _PyTraceMalloc_Config) _Py_tracemalloc_config;
#define _PyTraceMalloc_Config_INIT \
{.initialized = TRACEMALLOC_NOT_INITIALIZED, \
.tracing = 0, \
.max_nframe = 1, \
.use_domain = 0}
#ifdef __cplusplus
}
#endif

20
Lib/test/test_tracemalloc.py
View file

@ -111,6 +111,26 @@ def test_get_object_traceback(self):
traceback = tracemalloc.get_object_traceback(obj)
self.assertEqual(traceback, obj_traceback)
def test_new_reference(self):
tracemalloc.clear_traces()
# gc.collect() indirectly calls PyList_ClearFreeList()
support.gc_collect()
# Create a list and "destroy it": put it in the PyListObject free list
obj = []
obj = None
# Create a list which should reuse the previously created empty list
obj = []
nframe = tracemalloc.get_traceback_limit()
frames = get_frames(nframe, -3)
obj_traceback = tracemalloc.Traceback(frames)
traceback = tracemalloc.get_object_traceback(obj)
self.assertIsNotNone(traceback)
self.assertEqual(traceback, obj_traceback)
def test_set_traceback_limit(self):
obj_size = 10

3
Misc/NEWS.d/next/Library/2018-10-23-18-58-12.bpo-35053.G82qwh.rst Normal file
View file

@ -0,0 +1,3 @@
tracemalloc now tries to update the traceback when an object is reused from a
"free list" (optimization for faster object creation, used by the builtin list
type for example).

135
Modules/_tracemalloc.c
View file

@ -29,27 +29,6 @@ static struct {
PyMemAllocatorEx obj;
} allocators;
static struct {
/* Module initialized?
Variable protected by the GIL */
enum {
TRACEMALLOC_NOT_INITIALIZED,
TRACEMALLOC_INITIALIZED,
TRACEMALLOC_FINALIZED
} initialized;
/* Is tracemalloc tracing memory allocations?
Variable protected by the GIL */
int tracing;
/* limit of the number of frames in a traceback, 1 by default.
Variable protected by the GIL. */
int max_nframe;
/* use domain in trace key?
Variable protected by the GIL. */
int use_domain;
} tracemalloc_config = {TRACEMALLOC_NOT_INITIALIZED, 0, 1, 0};
#if defined(TRACE_RAW_MALLOC)
/* This lock is needed because tracemalloc_free() is called without
@ -459,7 +438,7 @@ traceback_get_frames(traceback_t *traceback)
tracemalloc_get_frame(pyframe, &traceback->frames[traceback->nframe]);
assert(traceback->frames[traceback->nframe].filename != NULL);
traceback->nframe++;
if (traceback->nframe == tracemalloc_config.max_nframe)
if (traceback->nframe == _Py_tracemalloc_config.max_nframe)
break;
}
}
@ -540,7 +519,7 @@ tracemalloc_use_domain(void)
{
_Py_hashtable_t *new_traces = NULL;
assert(!tracemalloc_config.use_domain);
assert(!_Py_tracemalloc_config.use_domain);
new_traces = hashtable_new(sizeof(pointer_t),
sizeof(trace_t),
@ -560,7 +539,7 @@ tracemalloc_use_domain(void)
_Py_hashtable_destroy(tracemalloc_traces);
tracemalloc_traces = new_traces;
tracemalloc_config.use_domain = 1;
_Py_tracemalloc_config.use_domain = 1;
return 0;
}
@ -572,9 +551,9 @@ tracemalloc_remove_trace(unsigned int domain, uintptr_t ptr)
trace_t trace;
int removed;
assert(tracemalloc_config.tracing);
assert(_Py_tracemalloc_config.tracing);
if (tracemalloc_config.use_domain) {
if (_Py_tracemalloc_config.use_domain) {
pointer_t key = {ptr, domain};
removed = _Py_HASHTABLE_POP(tracemalloc_traces, key, trace);
}
@ -603,14 +582,14 @@ tracemalloc_add_trace(unsigned int domain, uintptr_t ptr,
_Py_hashtable_entry_t* entry;
int res;
assert(tracemalloc_config.tracing);
assert(_Py_tracemalloc_config.tracing);
traceback = traceback_new();
if (traceback == NULL) {
return -1;
}
if (!tracemalloc_config.use_domain && domain != DEFAULT_DOMAIN) {
if (!_Py_tracemalloc_config.use_domain && domain != DEFAULT_DOMAIN) {
/* first trace using a non-zero domain whereas traces use compact
(uintptr_t) keys: switch to pointer_t keys. */
if (tracemalloc_use_domain() < 0) {
@ -618,7 +597,7 @@ tracemalloc_add_trace(unsigned int domain, uintptr_t ptr,
}
}
if (tracemalloc_config.use_domain) {
if (_Py_tracemalloc_config.use_domain) {
entry = _Py_HASHTABLE_GET_ENTRY(tracemalloc_traces, key);
}
else {
@ -639,7 +618,7 @@ tracemalloc_add_trace(unsigned int domain, uintptr_t ptr,
trace.size = size;
trace.traceback = traceback;
if (tracemalloc_config.use_domain) {
if (_Py_tracemalloc_config.use_domain) {
res = _Py_HASHTABLE_SET(tracemalloc_traces, key, trace);
}
else {
@ -956,13 +935,13 @@ tracemalloc_clear_traces(void)
static int
tracemalloc_init(void)
{
if (tracemalloc_config.initialized == TRACEMALLOC_FINALIZED) {
if (_Py_tracemalloc_config.initialized == TRACEMALLOC_FINALIZED) {
PyErr_SetString(PyExc_RuntimeError,
"the tracemalloc module has been unloaded");
return -1;
}
if (tracemalloc_config.initialized == TRACEMALLOC_INITIALIZED)
if (_Py_tracemalloc_config.initialized == TRACEMALLOC_INITIALIZED)
return 0;
PyMem_GetAllocator(PYMEM_DOMAIN_RAW, &allocators.raw);
@ -996,7 +975,7 @@ tracemalloc_init(void)
hashtable_hash_traceback,
hashtable_compare_traceback);
if (tracemalloc_config.use_domain) {
if (_Py_tracemalloc_config.use_domain) {
tracemalloc_traces = hashtable_new(sizeof(pointer_t),
sizeof(trace_t),
hashtable_hash_pointer_t,
@ -1026,7 +1005,7 @@ tracemalloc_init(void)
tracemalloc_empty_traceback.frames[0].lineno = 0;
tracemalloc_empty_traceback.hash = traceback_hash(&tracemalloc_empty_traceback);
tracemalloc_config.initialized = TRACEMALLOC_INITIALIZED;
_Py_tracemalloc_config.initialized = TRACEMALLOC_INITIALIZED;
return 0;
}
@ -1034,9 +1013,9 @@ tracemalloc_init(void)
static void
tracemalloc_deinit(void)
{
if (tracemalloc_config.initialized != TRACEMALLOC_INITIALIZED)
if (_Py_tracemalloc_config.initialized != TRACEMALLOC_INITIALIZED)
return;
tracemalloc_config.initialized = TRACEMALLOC_FINALIZED;
_Py_tracemalloc_config.initialized = TRACEMALLOC_FINALIZED;
tracemalloc_stop();
@ -1077,13 +1056,13 @@ tracemalloc_start(int max_nframe)
return -1;
}
if (tracemalloc_config.tracing) {
if (_Py_tracemalloc_config.tracing) {
/* hook already installed: do nothing */
return 0;
}
assert(1 <= max_nframe && max_nframe <= MAX_NFRAME);
tracemalloc_config.max_nframe = max_nframe;
_Py_tracemalloc_config.max_nframe = max_nframe;
/* allocate a buffer to store a new traceback */
size = TRACEBACK_SIZE(max_nframe);
@ -1119,7 +1098,7 @@ tracemalloc_start(int max_nframe)
PyMem_SetAllocator(PYMEM_DOMAIN_OBJ, &alloc);
/* everything is ready: start tracing Python memory allocations */
tracemalloc_config.tracing = 1;
_Py_tracemalloc_config.tracing = 1;
return 0;
}
@ -1128,11 +1107,11 @@ tracemalloc_start(int max_nframe)
static void
tracemalloc_stop(void)
{
if (!tracemalloc_config.tracing)
if (!_Py_tracemalloc_config.tracing)
return;
/* stop tracing Python memory allocations */
tracemalloc_config.tracing = 0;
_Py_tracemalloc_config.tracing = 0;
/* unregister the hook on memory allocators */
#ifdef TRACE_RAW_MALLOC
@ -1160,7 +1139,7 @@ static PyObject *
_tracemalloc_is_tracing_impl(PyObject *module)
/*[clinic end generated code: output=2d763b42601cd3ef input=af104b0a00192f63]*/
{
return PyBool_FromLong(tracemalloc_config.tracing);
return PyBool_FromLong(_Py_tracemalloc_config.tracing);
}
@ -1174,7 +1153,7 @@ static PyObject *
_tracemalloc_clear_traces_impl(PyObject *module)
/*[clinic end generated code: output=a86080ee41b84197 input=0dab5b6c785183a5]*/
{
if (!tracemalloc_config.tracing)
if (!_Py_tracemalloc_config.tracing)
Py_RETURN_NONE;
set_reentrant(1);
@ -1299,7 +1278,7 @@ tracemalloc_get_traces_fill(_Py_hashtable_t *traces, _Py_hashtable_entry_t *entr
PyObject *tracemalloc_obj;
int res;
if (tracemalloc_config.use_domain) {
if (_Py_tracemalloc_config.use_domain) {
pointer_t key;
_Py_HASHTABLE_ENTRY_READ_KEY(traces, entry, key);
domain = key.domain;
@ -1359,7 +1338,7 @@ _tracemalloc__get_traces_impl(PyObject *module)
if (get_traces.list == NULL)
goto error;
if (!tracemalloc_config.tracing)
if (!_Py_tracemalloc_config.tracing)
return get_traces.list;
/* the traceback hash table is used temporarily to intern traceback tuple
@ -1414,11 +1393,11 @@ tracemalloc_get_traceback(unsigned int domain, uintptr_t ptr)
trace_t trace;
int found;
if (!tracemalloc_config.tracing)
if (!_Py_tracemalloc_config.tracing)
return NULL;
TABLES_LOCK();
if (tracemalloc_config.use_domain) {
if (_Py_tracemalloc_config.use_domain) {
pointer_t key = {ptr, domain};
found = _Py_HASHTABLE_GET(tracemalloc_traces, key, trace);
}
@ -1558,7 +1537,7 @@ static PyObject *
_tracemalloc_get_traceback_limit_impl(PyObject *module)
/*[clinic end generated code: output=d556d9306ba95567 input=da3cd977fc68ae3b]*/
{
return PyLong_FromLong(tracemalloc_config.max_nframe);
return PyLong_FromLong(_Py_tracemalloc_config.max_nframe);
}
@ -1603,7 +1582,7 @@ _tracemalloc_get_traced_memory_impl(PyObject *module)
{
Py_ssize_t size, peak_size;
if (!tracemalloc_config.tracing)
if (!_Py_tracemalloc_config.tracing)
return Py_BuildValue("ii", 0, 0);
TABLES_LOCK();
@ -1681,7 +1660,7 @@ PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
int res;
PyGILState_STATE gil_state;
if (!tracemalloc_config.tracing) {
if (!_Py_tracemalloc_config.tracing) {
/* tracemalloc is not tracing: do nothing */
return -2;
}
@ -1700,7 +1679,7 @@ PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
int
PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr)
{
if (!tracemalloc_config.tracing) {
if (!_Py_tracemalloc_config.tracing) {
/* tracemalloc is not tracing: do nothing */
return -2;
}
@ -1713,6 +1692,60 @@ PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr)
}
/* If the object memory block is already traced, update its trace
with the current Python traceback.
Do nothing if tracemalloc is not tracing memory allocations
or if the object memory block is not already traced. */
int
_PyTraceMalloc_NewReference(PyObject *op)
{
assert(PyGILState_Check());
if (!_Py_tracemalloc_config.tracing) {
/* tracemalloc is not tracing: do nothing */
return -1;
}
uintptr_t ptr;
PyTypeObject *type = Py_TYPE(op);
if (PyType_IS_GC(type)) {
ptr = (uintptr_t)((char *)op - sizeof(PyGC_Head));
}
else {
ptr = (uintptr_t)op;
}
_Py_hashtable_entry_t* entry;
int res = -1;
TABLES_LOCK();
if (_Py_tracemalloc_config.use_domain) {
pointer_t key = {ptr, DEFAULT_DOMAIN};
entry = _Py_HASHTABLE_GET_ENTRY(tracemalloc_traces, key);
}
else {
entry = _Py_HASHTABLE_GET_ENTRY(tracemalloc_traces, ptr);
}
if (entry != NULL) {
/* update the traceback of the memory block */
traceback_t *traceback = traceback_new();
if (traceback != NULL) {
trace_t trace;
_Py_HASHTABLE_ENTRY_READ_DATA(tracemalloc_traces, entry, trace);
trace.traceback = traceback;
_Py_HASHTABLE_ENTRY_WRITE_DATA(tracemalloc_traces, entry, trace);
res = 0;
}
}
/* else: cannot track the object, its memory block size is unknown */
TABLES_UNLOCK();
return res;
}
PyObject*
_PyTraceMalloc_GetTraceback(unsigned int domain, uintptr_t ptr)
{

3
Objects/object.c
View file

@ -1919,6 +1919,9 @@ _Py_ReadyTypes(void)
void
_Py_NewReference(PyObject *op)
{
if (_Py_tracemalloc_config.tracing) {
_PyTraceMalloc_NewReference(op);
}
_Py_INC_REFTOTAL;
op->ob_refcnt = 1;
_Py_AddToAllObjects(op, 1);

6
Objects/obmalloc.c
View file

@ -63,6 +63,12 @@ static void* _PyObject_Realloc(void *ctx, void *ptr, size_t size);
#endif
/* bpo-35053: Declare tracemalloc configuration here rather than
Modules/_tracemalloc.c because _tracemalloc can be compiled as dynamic
library, whereas _Py_NewReference() requires it. */
struct _PyTraceMalloc_Config _Py_tracemalloc_config = _PyTraceMalloc_Config_INIT;
static void *
_PyMem_RawMalloc(void *ctx, size_t size)
{