bpo-30860: Consolidate stateful runtime globals. (#3397)
* group the (stateful) runtime globals into various topical structs
* consolidate the topical structs under a single top-level _PyRuntimeState struct
* add a check-c-globals.py script that helps identify runtime globals
Other globals are excluded (see globals.txt and check-c-globals.py).
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 4e5acf3..832e27e 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -24,6 +24,8 @@
*/
#include "Python.h"
+#include "internal/mem.h"
+#include "internal/pystate.h"
#include "frameobject.h" /* for PyFrame_ClearFreeList */
#include "pydtrace.h"
#include "pytime.h" /* for _PyTime_GetMonotonicClock() */
@@ -39,133 +41,9 @@
/* Get the object given the GC head */
#define FROM_GC(g) ((PyObject *)(((PyGC_Head *)g)+1))
-/*** Global GC state ***/
-
-struct gc_generation {
- PyGC_Head head;
- int threshold; /* collection threshold */
- int count; /* count of allocations or collections of younger
- generations */
-};
-
-/* If we change this, we need to change the default value in the signature of
- gc.collect. */
-#define NUM_GENERATIONS 3
-#define GEN_HEAD(n) (&generations[n].head)
-
-/* linked lists of container objects */
-static struct gc_generation generations[NUM_GENERATIONS] = {
- /* PyGC_Head, threshold, count */
- {{{GEN_HEAD(0), GEN_HEAD(0), 0}}, 700, 0},
- {{{GEN_HEAD(1), GEN_HEAD(1), 0}}, 10, 0},
- {{{GEN_HEAD(2), GEN_HEAD(2), 0}}, 10, 0},
-};
-
-PyGC_Head *_PyGC_generation0 = GEN_HEAD(0);
-
-static int enabled = 1; /* automatic collection enabled? */
-
-/* true if we are currently running the collector */
-static int collecting = 0;
-
-/* list of uncollectable objects */
-static PyObject *garbage = NULL;
-
/* Python string to use if unhandled exception occurs */
static PyObject *gc_str = NULL;
-/* a list of callbacks to be invoked when collection is performed */
-static PyObject *callbacks = NULL;
-
-/* This is the number of objects that survived the last full collection. It
- approximates the number of long lived objects tracked by the GC.
-
- (by "full collection", we mean a collection of the oldest generation).
-*/
-static Py_ssize_t long_lived_total = 0;
-
-/* This is the number of objects that survived all "non-full" collections,
- and are awaiting to undergo a full collection for the first time.
-
-*/
-static Py_ssize_t long_lived_pending = 0;
-
-/*
- NOTE: about the counting of long-lived objects.
-
- To limit the cost of garbage collection, there are two strategies;
- - make each collection faster, e.g. by scanning fewer objects
- - do less collections
- This heuristic is about the latter strategy.
-
- In addition to the various configurable thresholds, we only trigger a
- full collection if the ratio
- long_lived_pending / long_lived_total
- is above a given value (hardwired to 25%).
-
- The reason is that, while "non-full" collections (i.e., collections of
- the young and middle generations) will always examine roughly the same
- number of objects -- determined by the aforementioned thresholds --,
- the cost of a full collection is proportional to the total number of
- long-lived objects, which is virtually unbounded.
-
- Indeed, it has been remarked that doing a full collection every
- <constant number> of object creations entails a dramatic performance
- degradation in workloads which consist in creating and storing lots of
- long-lived objects (e.g. building a large list of GC-tracked objects would
- show quadratic performance, instead of linear as expected: see issue #4074).
-
- Using the above ratio, instead, yields amortized linear performance in
- the total number of objects (the effect of which can be summarized
- thusly: "each full garbage collection is more and more costly as the
- number of objects grows, but we do fewer and fewer of them").
-
- This heuristic was suggested by Martin von Löwis on python-dev in
- June 2008. His original analysis and proposal can be found at:
- http://mail.python.org/pipermail/python-dev/2008-June/080579.html
-*/
-
-/*
- NOTE: about untracking of mutable objects.
-
- Certain types of container cannot participate in a reference cycle, and
- so do not need to be tracked by the garbage collector. Untracking these
- objects reduces the cost of garbage collections. However, determining
- which objects may be untracked is not free, and the costs must be
- weighed against the benefits for garbage collection.
-
- There are two possible strategies for when to untrack a container:
-
- i) When the container is created.
- ii) When the container is examined by the garbage collector.
-
- Tuples containing only immutable objects (integers, strings etc, and
- recursively, tuples of immutable objects) do not need to be tracked.
- The interpreter creates a large number of tuples, many of which will
- not survive until garbage collection. It is therefore not worthwhile
- to untrack eligible tuples at creation time.
-
- Instead, all tuples except the empty tuple are tracked when created.
- During garbage collection it is determined whether any surviving tuples
- can be untracked. A tuple can be untracked if all of its contents are
- already not tracked. Tuples are examined for untracking in all garbage
- collection cycles. It may take more than one cycle to untrack a tuple.
-
- Dictionaries containing only immutable objects also do not need to be
- tracked. Dictionaries are untracked when created. If a tracked item is
- inserted into a dictionary (either as a key or value), the dictionary
- becomes tracked. During a full garbage collection (all generations),
- the collector will untrack any dictionaries whose contents are not
- tracked.
-
- The module provides the python function is_tracked(obj), which returns
- the CURRENT tracking status of the object. Subsequent garbage
- collections may change the tracking status of the object.
-
- Untracking of certain containers was introduced in issue #4688, and
- the algorithm was refined in response to issue #14775.
-*/
-
/* set for debugging information */
#define DEBUG_STATS (1<<0) /* print collection statistics */
#define DEBUG_COLLECTABLE (1<<1) /* print collectable objects */
@@ -174,19 +52,26 @@
#define DEBUG_LEAK DEBUG_COLLECTABLE | \
DEBUG_UNCOLLECTABLE | \
DEBUG_SAVEALL
-static int debug;
-/* Running stats per generation */
-struct gc_generation_stats {
- /* total number of collections */
- Py_ssize_t collections;
- /* total number of collected objects */
- Py_ssize_t collected;
- /* total number of uncollectable objects (put into gc.garbage) */
- Py_ssize_t uncollectable;
-};
+#define GEN_HEAD(n) (&_PyRuntime.gc.generations[n].head)
-static struct gc_generation_stats generation_stats[NUM_GENERATIONS];
+void
+_PyGC_Initialize(struct _gc_runtime_state *state)
+{
+ state->enabled = 1; /* automatic collection enabled? */
+
+#define _GEN_HEAD(n) (&state->generations[n].head)
+ struct gc_generation generations[NUM_GENERATIONS] = {
+ /* PyGC_Head, threshold, count */
+ {{{_GEN_HEAD(0), _GEN_HEAD(0), 0}}, 700, 0},
+ {{{_GEN_HEAD(1), _GEN_HEAD(1), 0}}, 10, 0},
+ {{{_GEN_HEAD(2), _GEN_HEAD(2), 0}}, 10, 0},
+ };
+ for (int i = 0; i < NUM_GENERATIONS; i++) {
+ state->generations[i] = generations[i];
+ };
+ state->generation0 = GEN_HEAD(0);
+}
/*--------------------------------------------------------------------------
gc_refs values.
@@ -766,16 +651,16 @@
{
PyGC_Head *gc = finalizers->gc.gc_next;
- if (garbage == NULL) {
- garbage = PyList_New(0);
- if (garbage == NULL)
+ if (_PyRuntime.gc.garbage == NULL) {
+ _PyRuntime.gc.garbage = PyList_New(0);
+ if (_PyRuntime.gc.garbage == NULL)
Py_FatalError("gc couldn't create gc.garbage list");
}
for (; gc != finalizers; gc = gc->gc.gc_next) {
PyObject *op = FROM_GC(gc);
- if ((debug & DEBUG_SAVEALL) || has_legacy_finalizer(op)) {
- if (PyList_Append(garbage, op) < 0)
+ if ((_PyRuntime.gc.debug & DEBUG_SAVEALL) || has_legacy_finalizer(op)) {
+ if (PyList_Append(_PyRuntime.gc.garbage, op) < 0)
return -1;
}
}
@@ -865,8 +750,8 @@
PyGC_Head *gc = collectable->gc.gc_next;
PyObject *op = FROM_GC(gc);
- if (debug & DEBUG_SAVEALL) {
- PyList_Append(garbage, op);
+ if (_PyRuntime.gc.debug & DEBUG_SAVEALL) {
+ PyList_Append(_PyRuntime.gc.garbage, op);
}
else {
if ((clear = Py_TYPE(op)->tp_clear) != NULL) {
@@ -919,9 +804,9 @@
PyGC_Head *gc;
_PyTime_t t1 = 0; /* initialize to prevent a compiler warning */
- struct gc_generation_stats *stats = &generation_stats[generation];
+ struct gc_generation_stats *stats = &_PyRuntime.gc.generation_stats[generation];
- if (debug & DEBUG_STATS) {
+ if (_PyRuntime.gc.debug & DEBUG_STATS) {
PySys_WriteStderr("gc: collecting generation %d...\n",
generation);
PySys_WriteStderr("gc: objects in each generation:");
@@ -938,9 +823,9 @@
/* update collection and allocation counters */
if (generation+1 < NUM_GENERATIONS)
- generations[generation+1].count += 1;
+ _PyRuntime.gc.generations[generation+1].count += 1;
for (i = 0; i <= generation; i++)
- generations[i].count = 0;
+ _PyRuntime.gc.generations[i].count = 0;
/* merge younger generations with one we are currently collecting */
for (i = 0; i < generation; i++) {
@@ -974,7 +859,7 @@
/* Move reachable objects to next generation. */
if (young != old) {
if (generation == NUM_GENERATIONS - 2) {
- long_lived_pending += gc_list_size(young);
+ _PyRuntime.gc.long_lived_pending += gc_list_size(young);
}
gc_list_merge(young, old);
}
@@ -982,8 +867,8 @@
/* We only untrack dicts in full collections, to avoid quadratic
dict build-up. See issue #14775. */
untrack_dicts(young);
- long_lived_pending = 0;
- long_lived_total = gc_list_size(young);
+ _PyRuntime.gc.long_lived_pending = 0;
+ _PyRuntime.gc.long_lived_total = gc_list_size(young);
}
/* All objects in unreachable are trash, but objects reachable from
@@ -1003,7 +888,7 @@
for (gc = unreachable.gc.gc_next; gc != &unreachable;
gc = gc->gc.gc_next) {
m++;
- if (debug & DEBUG_COLLECTABLE) {
+ if (_PyRuntime.gc.debug & DEBUG_COLLECTABLE) {
debug_cycle("collectable", FROM_GC(gc));
}
}
@@ -1032,10 +917,10 @@
gc != &finalizers;
gc = gc->gc.gc_next) {
n++;
- if (debug & DEBUG_UNCOLLECTABLE)
+ if (_PyRuntime.gc.debug & DEBUG_UNCOLLECTABLE)
debug_cycle("uncollectable", FROM_GC(gc));
}
- if (debug & DEBUG_STATS) {
+ if (_PyRuntime.gc.debug & DEBUG_STATS) {
_PyTime_t t2 = _PyTime_GetMonotonicClock();
if (m == 0 && n == 0)
@@ -1098,11 +983,11 @@
PyObject *info = NULL;
/* we may get called very early */
- if (callbacks == NULL)
+ if (_PyRuntime.gc.callbacks == NULL)
return;
/* The local variable cannot be rebound, check it for sanity */
- assert(callbacks != NULL && PyList_CheckExact(callbacks));
- if (PyList_GET_SIZE(callbacks) != 0) {
+ assert(_PyRuntime.gc.callbacks != NULL && PyList_CheckExact(_PyRuntime.gc.callbacks));
+ if (PyList_GET_SIZE(_PyRuntime.gc.callbacks) != 0) {
info = Py_BuildValue("{sisnsn}",
"generation", generation,
"collected", collected,
@@ -1112,8 +997,8 @@
return;
}
}
- for (i=0; i<PyList_GET_SIZE(callbacks); i++) {
- PyObject *r, *cb = PyList_GET_ITEM(callbacks, i);
+ for (i=0; i<PyList_GET_SIZE(_PyRuntime.gc.callbacks); i++) {
+ PyObject *r, *cb = PyList_GET_ITEM(_PyRuntime.gc.callbacks, i);
Py_INCREF(cb); /* make sure cb doesn't go away */
r = PyObject_CallFunction(cb, "sO", phase, info);
Py_XDECREF(r);
@@ -1147,13 +1032,13 @@
* exceeds the threshold. Objects in the that generation and
* generations younger than it will be collected. */
for (i = NUM_GENERATIONS-1; i >= 0; i--) {
- if (generations[i].count > generations[i].threshold) {
+ if (_PyRuntime.gc.generations[i].count > _PyRuntime.gc.generations[i].threshold) {
/* Avoid quadratic performance degradation in number
of tracked objects. See comments at the beginning
of this file, and issue #4074.
*/
if (i == NUM_GENERATIONS - 1
- && long_lived_pending < long_lived_total / 4)
+ && _PyRuntime.gc.long_lived_pending < _PyRuntime.gc.long_lived_total / 4)
continue;
n = collect_with_callback(i);
break;
@@ -1174,7 +1059,7 @@
gc_enable_impl(PyObject *module)
/*[clinic end generated code: output=45a427e9dce9155c input=81ac4940ca579707]*/
{
- enabled = 1;
+ _PyRuntime.gc.enabled = 1;
Py_RETURN_NONE;
}
@@ -1188,7 +1073,7 @@
gc_disable_impl(PyObject *module)
/*[clinic end generated code: output=97d1030f7aa9d279 input=8c2e5a14e800d83b]*/
{
- enabled = 0;
+ _PyRuntime.gc.enabled = 0;
Py_RETURN_NONE;
}
@@ -1202,7 +1087,7 @@
gc_isenabled_impl(PyObject *module)
/*[clinic end generated code: output=1874298331c49130 input=30005e0422373b31]*/
{
- return enabled;
+ return _PyRuntime.gc.enabled;
}
/*[clinic input]
@@ -1230,12 +1115,12 @@
return -1;
}
- if (collecting)
+ if (_PyRuntime.gc.collecting)
n = 0; /* already collecting, don't do anything */
else {
- collecting = 1;
+ _PyRuntime.gc.collecting = 1;
n = collect_with_callback(generation);
- collecting = 0;
+ _PyRuntime.gc.collecting = 0;
}
return n;
@@ -1263,7 +1148,7 @@
gc_set_debug_impl(PyObject *module, int flags)
/*[clinic end generated code: output=7c8366575486b228 input=5e5ce15e84fbed15]*/
{
- debug = flags;
+ _PyRuntime.gc.debug = flags;
Py_RETURN_NONE;
}
@@ -1278,7 +1163,7 @@
gc_get_debug_impl(PyObject *module)
/*[clinic end generated code: output=91242f3506cd1e50 input=91a101e1c3b98366]*/
{
- return debug;
+ return _PyRuntime.gc.debug;
}
PyDoc_STRVAR(gc_set_thresh__doc__,
@@ -1292,13 +1177,13 @@
{
int i;
if (!PyArg_ParseTuple(args, "i|ii:set_threshold",
- &generations[0].threshold,
- &generations[1].threshold,
- &generations[2].threshold))
+ &_PyRuntime.gc.generations[0].threshold,
+ &_PyRuntime.gc.generations[1].threshold,
+ &_PyRuntime.gc.generations[2].threshold))
return NULL;
for (i = 2; i < NUM_GENERATIONS; i++) {
/* generations higher than 2 get the same threshold */
- generations[i].threshold = generations[2].threshold;
+ _PyRuntime.gc.generations[i].threshold = _PyRuntime.gc.generations[2].threshold;
}
Py_RETURN_NONE;
@@ -1315,9 +1200,9 @@
/*[clinic end generated code: output=7902bc9f41ecbbd8 input=286d79918034d6e6]*/
{
return Py_BuildValue("(iii)",
- generations[0].threshold,
- generations[1].threshold,
- generations[2].threshold);
+ _PyRuntime.gc.generations[0].threshold,
+ _PyRuntime.gc.generations[1].threshold,
+ _PyRuntime.gc.generations[2].threshold);
}
/*[clinic input]
@@ -1331,9 +1216,9 @@
/*[clinic end generated code: output=354012e67b16398f input=a392794a08251751]*/
{
return Py_BuildValue("(iii)",
- generations[0].count,
- generations[1].count,
- generations[2].count);
+ _PyRuntime.gc.generations[0].count,
+ _PyRuntime.gc.generations[1].count,
+ _PyRuntime.gc.generations[2].count);
}
static int
@@ -1464,7 +1349,7 @@
/* To get consistent values despite allocations while constructing
the result list, we use a snapshot of the running stats. */
for (i = 0; i < NUM_GENERATIONS; i++) {
- stats[i] = generation_stats[i];
+ stats[i] = _PyRuntime.gc.generation_stats[i];
}
result = PyList_New(0);
@@ -1581,22 +1466,22 @@
if (m == NULL)
return NULL;
- if (garbage == NULL) {
- garbage = PyList_New(0);
- if (garbage == NULL)
+ if (_PyRuntime.gc.garbage == NULL) {
+ _PyRuntime.gc.garbage = PyList_New(0);
+ if (_PyRuntime.gc.garbage == NULL)
return NULL;
}
- Py_INCREF(garbage);
- if (PyModule_AddObject(m, "garbage", garbage) < 0)
+ Py_INCREF(_PyRuntime.gc.garbage);
+ if (PyModule_AddObject(m, "garbage", _PyRuntime.gc.garbage) < 0)
return NULL;
- if (callbacks == NULL) {
- callbacks = PyList_New(0);
- if (callbacks == NULL)
+ if (_PyRuntime.gc.callbacks == NULL) {
+ _PyRuntime.gc.callbacks = PyList_New(0);
+ if (_PyRuntime.gc.callbacks == NULL)
return NULL;
}
- Py_INCREF(callbacks);
- if (PyModule_AddObject(m, "callbacks", callbacks) < 0)
+ Py_INCREF(_PyRuntime.gc.callbacks);
+ if (PyModule_AddObject(m, "callbacks", _PyRuntime.gc.callbacks) < 0)
return NULL;
#define ADD_INT(NAME) if (PyModule_AddIntConstant(m, #NAME, NAME) < 0) return NULL
@@ -1615,12 +1500,12 @@
{
Py_ssize_t n;
- if (collecting)
+ if (_PyRuntime.gc.collecting)
n = 0; /* already collecting, don't do anything */
else {
- collecting = 1;
+ _PyRuntime.gc.collecting = 1;
n = collect_with_callback(NUM_GENERATIONS - 1);
- collecting = 0;
+ _PyRuntime.gc.collecting = 0;
}
return n;
@@ -1629,7 +1514,7 @@
Py_ssize_t
_PyGC_CollectIfEnabled(void)
{
- if (!enabled)
+ if (!_PyRuntime.gc.enabled)
return 0;
return PyGC_Collect();
@@ -1646,12 +1531,12 @@
during interpreter shutdown (and then never finish it).
See http://bugs.python.org/issue8713#msg195178 for an example.
*/
- if (collecting)
+ if (_PyRuntime.gc.collecting)
n = 0;
else {
- collecting = 1;
+ _PyRuntime.gc.collecting = 1;
n = collect(NUM_GENERATIONS - 1, NULL, NULL, 1);
- collecting = 0;
+ _PyRuntime.gc.collecting = 0;
}
return n;
}
@@ -1659,10 +1544,10 @@
void
_PyGC_DumpShutdownStats(void)
{
- if (!(debug & DEBUG_SAVEALL)
- && garbage != NULL && PyList_GET_SIZE(garbage) > 0) {
+ if (!(_PyRuntime.gc.debug & DEBUG_SAVEALL)
+ && _PyRuntime.gc.garbage != NULL && PyList_GET_SIZE(_PyRuntime.gc.garbage) > 0) {
char *message;
- if (debug & DEBUG_UNCOLLECTABLE)
+ if (_PyRuntime.gc.debug & DEBUG_UNCOLLECTABLE)
message = "gc: %zd uncollectable objects at " \
"shutdown";
else
@@ -1673,13 +1558,13 @@
already. */
if (PyErr_WarnExplicitFormat(PyExc_ResourceWarning, "gc", 0,
"gc", NULL, message,
- PyList_GET_SIZE(garbage)))
+ PyList_GET_SIZE(_PyRuntime.gc.garbage)))
PyErr_WriteUnraisable(NULL);
- if (debug & DEBUG_UNCOLLECTABLE) {
+ if (_PyRuntime.gc.debug & DEBUG_UNCOLLECTABLE) {
PyObject *repr = NULL, *bytes = NULL;
- repr = PyObject_Repr(garbage);
+ repr = PyObject_Repr(_PyRuntime.gc.garbage);
if (!repr || !(bytes = PyUnicode_EncodeFSDefault(repr)))
- PyErr_WriteUnraisable(garbage);
+ PyErr_WriteUnraisable(_PyRuntime.gc.garbage);
else {
PySys_WriteStderr(
" %s\n",
@@ -1695,7 +1580,7 @@
void
_PyGC_Fini(void)
{
- Py_CLEAR(callbacks);
+ Py_CLEAR(_PyRuntime.gc.callbacks);
}
/* for debugging */
@@ -1746,15 +1631,15 @@
return PyErr_NoMemory();
g->gc.gc_refs = 0;
_PyGCHead_SET_REFS(g, GC_UNTRACKED);
- generations[0].count++; /* number of allocated GC objects */
- if (generations[0].count > generations[0].threshold &&
- enabled &&
- generations[0].threshold &&
- !collecting &&
+ _PyRuntime.gc.generations[0].count++; /* number of allocated GC objects */
+ if (_PyRuntime.gc.generations[0].count > _PyRuntime.gc.generations[0].threshold &&
+ _PyRuntime.gc.enabled &&
+ _PyRuntime.gc.generations[0].threshold &&
+ !_PyRuntime.gc.collecting &&
!PyErr_Occurred()) {
- collecting = 1;
+ _PyRuntime.gc.collecting = 1;
collect_generations();
- collecting = 0;
+ _PyRuntime.gc.collecting = 0;
}
op = FROM_GC(g);
return op;
@@ -1819,8 +1704,8 @@
PyGC_Head *g = AS_GC(op);
if (IS_TRACKED(op))
gc_list_remove(g);
- if (generations[0].count > 0) {
- generations[0].count--;
+ if (_PyRuntime.gc.generations[0].count > 0) {
+ _PyRuntime.gc.generations[0].count--;
}
PyObject_FREE(g);
}