mirror of
https://github.com/python/cpython.git
synced 2024-11-28 08:20:55 +01:00
117 lines
4.5 KiB
Plaintext
117 lines
4.5 KiB
Plaintext
This file describes some special Python build types enabled via
|
|
compile-time preprocessor defines.
|
|
|
|
---------------------------------------------------------------------------
|
|
Py_REF_DEBUG
|
|
|
|
Turn on aggregate reference counting. This arranges that extern
|
|
_Py_RefTotal hold a count of all references, the sum of ob_refcnt across
|
|
all objects. In a debug-mode build, this is where the "8288" comes from
|
|
in
|
|
|
|
>>> 23
|
|
23
|
|
[8288 refs]
|
|
>>>
|
|
|
|
Note that if this count increases when you're not storing away new objects,
|
|
there's probably a leak. Remember, though, that in interactive mode the
|
|
special name "_" holds a reference to the last result displayed!
|
|
|
|
Py_REF_DEBUG also checks after every decref to verify that the refcount
|
|
hasn't gone negative, and causes an immediate fatal error if it has.
|
|
|
|
Special gimmicks:
|
|
|
|
sys.gettotalrefcount()
|
|
Return current total of all refcounts.
|
|
Available under Py_REF_DEBUG in Python 2.3.
|
|
Before 2.3, Py_TRACE_REFS was required to enable this function.
|
|
---------------------------------------------------------------------------
|
|
Py_TRACE_REFS
|
|
|
|
Turn on heavy reference debugging. This is major surgery. Every PyObject
|
|
grows two more pointers, to maintain a doubly-linked list of all live
|
|
heap-allocated objects (note that, e.g., most builtin type objects are not
|
|
in this list, as they're statically allocated). Note that because the
|
|
fundamental PyObject layout changes, Python modules compiled with
|
|
Py_TRACE_REFS are incompatible with modules compiled without it.
|
|
|
|
Py_TRACE_REFS implies Py_REF_DEBUG.
|
|
|
|
Special gimmicks:
|
|
|
|
sys.getobjects(max[, type])
|
|
Return list of the most-recently allocated max objects, most recently
|
|
allocated first in the list, least-recently allocated last in the
|
|
list. max=0 means no limit on list length. If an optional type
|
|
object is passed, the list is also restricted to objects of that
|
|
type. The return list itself, and some temp objects created just
|
|
to call sys.getobjects(), are excluded from the return list.
|
|
|
|
envar PYTHONDUMPREFS
|
|
If this envar exists, Py_Finalize() arranges to print a list of
|
|
all still-live heap objects.
|
|
---------------------------------------------------------------------------
|
|
PYMALLOC_DEBUG
|
|
|
|
Special gimmicks:
|
|
|
|
envar PYTHONMALLOCSTATS
|
|
If this envar exists, a report of pymalloc summary statistics is
|
|
printed to stderr whenever a new arena is allocated, and also
|
|
by Py_Finalize().
|
|
---------------------------------------------------------------------------
|
|
Py_DEBUG
|
|
|
|
This is what is generally meant by "a debug build" of Python.
|
|
|
|
Py_DEBUG implies Py_REF_DEBUG, Py_TRACE_REFS, and PYMALLOC_DEBUG (if
|
|
WITH_PYMALLOC is enabled).
|
|
---------------------------------------------------------------------------
|
|
COUNT_ALLOCS
|
|
|
|
Each type object grows three new members:
|
|
|
|
/* Number of times an object of this type was allocated. */
|
|
int tp_allocs;
|
|
|
|
/* Number of times an object of this type was deallocated. */
|
|
int tp_frees;
|
|
|
|
/* Highwater mark: the maximum value of tp_allocs - tp_frees so
|
|
* far; or, IOW, the largest number of objects of this type alive at
|
|
* the same time.
|
|
*/
|
|
int tp_maxalloc;
|
|
|
|
Allocation and deallocation code keeps these counts up to date.
|
|
Py_Finalize() displays a summary of the info returned by sys.getcounts()
|
|
(see below), along with assorted other special allocation counts (like
|
|
the number of tuple allocations satisfied by a tuple free-list, the number
|
|
of 1-character strings allocated, etc).
|
|
|
|
Before Python 2.2, type objects were immortal, and the COUNT_ALLOCS
|
|
implementation relies on that. As of Python 2.2, heap-allocated type/
|
|
class objects can go away. COUNT_ALLOCS can blow up in 2.2 and 2.2.1
|
|
because of this; this was fixed in 2.2.2. Use of COUNT_ALLOCS makes
|
|
all heap-allocated type objects immortal, except for those for which no
|
|
object of that type is ever allocated.
|
|
|
|
Special gimmicks:
|
|
|
|
sys.getcounts()
|
|
Return a list of 4-tuples, one entry for each type object for which
|
|
at least one object of that type was allocated. Each tuple is of
|
|
the form:
|
|
|
|
(tp_name, tp_allocs, tp_frees, tp_maxalloc)
|
|
|
|
Each distinct type object gets a distinct entry in this list, even
|
|
if two or more type objects have the same tp_name (in which case
|
|
there's no way to distinguish them by looking at this list). The
|
|
list is ordered by time of first object allocation: the type object
|
|
for which the first allocation of an object of that type occurred
|
|
most recently is at the front of the list.
|
|
---------------------------------------------------------------------------
|