mirror of
https://github.com/python/cpython.git
synced 2024-11-24 08:52:25 +01:00
13a00078b8
Python built with "configure --with-trace-refs" (tracing references) is now ABI compatible with Python release build and debug build. Moreover, it now also supports the Limited API. Change Py_TRACE_REFS build: * Remove _PyObject_EXTRA_INIT macro. * The PyObject structure no longer has two extra members (_ob_prev and _ob_next). * Use a hash table (_Py_hashtable_t) to trace references (all objects): PyInterpreterState.object_state.refchain. * Py_TRACE_REFS build is now ABI compatible with release build and debug build. * Limited C API extensions can now be built with Py_TRACE_REFS: xxlimited, xxlimited_35, _testclinic_limited. * No longer rename PyModule_Create2() and PyModule_FromDefAndSpec2() functions to PyModule_Create2TraceRefs() and PyModule_FromDefAndSpec2TraceRefs(). * _Py_PrintReferenceAddresses() is now called before finalize_interp_delete() which deletes the refchain hash table. * test_tracemalloc find_trace() now also filters by size to ignore the memory allocated by _PyRefchain_Trace(). Test changes for Py_TRACE_REFS: * Add test.support.Py_TRACE_REFS constant. * Add test_sys.test_getobjects() to test sys.getobjects() function. * test_exceptions skips test_recursion_normalizing_with_no_memory() and test_memory_error_in_PyErr_PrintEx() if Python is built with Py_TRACE_REFS. * test_repl skips test_no_memory(). * test_capi skisp test_set_nomemory().
100 lines
3.8 KiB
Plaintext
100 lines
3.8 KiB
Plaintext
This file describes some special Python build types enabled via compile-time
|
|
preprocessor directives.
|
|
|
|
IMPORTANT: if you want to build a debug-enabled Python, it is recommended that
|
|
you use ``./configure --with-pydebug``, rather than the options listed here.
|
|
|
|
However, if you wish to define some of these options individually, it is best
|
|
to define them in the EXTRA_CFLAGS make variable;
|
|
``make EXTRA_CFLAGS="-DPy_REF_DEBUG"``.
|
|
|
|
|
|
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.
|
|
Passing ``-X showrefcount`` on the command line causes the interactive
|
|
interpreter to print the reference count total as well the number of memory
|
|
blocks allocated after each statement:
|
|
|
|
>>> 23
|
|
23
|
|
[8288 refs, 14332 blocks]
|
|
>>>
|
|
|
|
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.
|
|
|
|
Py_DEBUG implies Py_REF_DEBUG.
|
|
|
|
Special gimmicks:
|
|
|
|
sys.gettotalrefcount()
|
|
Return current total of all refcounts.
|
|
|
|
|
|
Py_TRACE_REFS
|
|
-------------
|
|
|
|
Build option: ``./configure --with-trace-refs``.
|
|
|
|
Turn on heavy reference debugging. This is major surgery. All live
|
|
heap-allocated objects are traced in a hash table. Most built-in type objects
|
|
are not in this list, as they're statically allocated.
|
|
|
|
Special gimmicks:
|
|
|
|
sys.getobjects(max[, type])
|
|
Return list of the (no more than) max most-recently allocated 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. Note that the list returned is just
|
|
another object, though, so may appear in the return list the next time you
|
|
call getobjects(); note that every object in the list is kept alive too,
|
|
simply by virtue of being in the list.
|
|
|
|
envvar PYTHONDUMPREFS
|
|
If this envvar exists, Py_FinalizeEx() arranges to print a list of all
|
|
still-live heap objects. This is printed twice, in different formats,
|
|
before and after Py_FinalizeEx has cleaned up everything it can clean up. The
|
|
first output block produces the repr() of each object so is more
|
|
informative; however, a lot of stuff destined to die is still alive then.
|
|
The second output block is much harder to work with (repr() can't be invoked
|
|
anymore -- the interpreter has been torn down too far), but doesn't list any
|
|
objects that will die. The tool script combinerefs.py can be run over this
|
|
to combine the info from both output blocks. The second output block, and
|
|
combinerefs.py, were new in Python 2.3b1.
|
|
|
|
|
|
Py_DEBUG
|
|
--------
|
|
|
|
This is what is generally meant by "a debug build" of Python.
|
|
|
|
Py_DEBUG implies LLTRACE and Py_REF_DEBUG. In addition, C assert()s are enabled
|
|
(via the C way: by not defining NDEBUG), and some routines do additional sanity
|
|
checks inside "#ifdef Py_DEBUG" blocks.
|
|
|
|
|
|
LLTRACE
|
|
-------
|
|
|
|
Compile in support for Low Level TRACE-ing of the main interpreter loop.
|
|
|
|
When this preprocessor symbol is defined, before PyEval_EvalFrame executes a
|
|
frame's code it checks the frame's global namespace for a variable
|
|
"__lltrace__". If such a variable is found, mounds of information about what
|
|
the interpreter is doing are sprayed to stdout, such as every opcode and opcode
|
|
argument and values pushed onto and popped off the value stack.
|
|
|
|
Not useful very often, but very useful when needed.
|
|
|
|
Py_DEBUG implies LLTRACE.
|