gh-108634: Py_TRACE_REFS uses a hash table (#108663)

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().

1 files changed, 11 insertions, 9 deletions

diff --git a/Lib/test/test_tracemalloc.py b/Lib/test/test_tracemalloc.py
index 4af4ca3..bea1245 100644
--- a/Lib/test/test_tracemalloc.py
+++ b/Lib/test/test_tracemalloc.py
@@ -173,9 +173,11 @@ class TestTracemallocEnabled(unittest.TestCase):
         self.assertEqual(len(traceback), 1)
         self.assertEqual(traceback, obj_traceback)
 
-    def find_trace(self, traces, traceback):
+    def find_trace(self, traces, traceback, size):
+        # filter also by size to ignore the memory allocated by
+        # _PyRefchain_Trace() if Python is built with Py_TRACE_REFS.
         for trace in traces:
-            if trace[2] == traceback._frames:
+            if trace[2] == traceback._frames and trace[1] == size:
                 return trace
 
         self.fail("trace not found")
@@ -186,11 +188,10 @@ class TestTracemallocEnabled(unittest.TestCase):
         obj, obj_traceback = allocate_bytes(obj_size)
 
         traces = tracemalloc._get_traces()
-        trace = self.find_trace(traces, obj_traceback)
+        trace = self.find_trace(traces, obj_traceback, obj_size)
 
         self.assertIsInstance(trace, tuple)
         domain, size, traceback, length = trace
-        self.assertEqual(size, obj_size)
         self.assertEqual(traceback, obj_traceback._frames)
 
         tracemalloc.stop()
@@ -208,17 +209,18 @@ class TestTracemallocEnabled(unittest.TestCase):
         # Ensure that two identical tracebacks are not duplicated
         tracemalloc.stop()
         tracemalloc.start(4)
-        obj_size = 123
-        obj1, obj1_traceback = allocate_bytes4(obj_size)
-        obj2, obj2_traceback = allocate_bytes4(obj_size)
+        obj1_size = 123
+        obj2_size = 125
+        obj1, obj1_traceback = allocate_bytes4(obj1_size)
+        obj2, obj2_traceback = allocate_bytes4(obj2_size)
 
         traces = tracemalloc._get_traces()
 
         obj1_traceback._frames = tuple(reversed(obj1_traceback._frames))
         obj2_traceback._frames = tuple(reversed(obj2_traceback._frames))
 
-        trace1 = self.find_trace(traces, obj1_traceback)
-        trace2 = self.find_trace(traces, obj2_traceback)
+        trace1 = self.find_trace(traces, obj1_traceback, obj1_size)
+        trace2 = self.find_trace(traces, obj2_traceback, obj2_size)
         domain1, size1, traceback1, length1 = trace1
         domain2, size2, traceback2, length2 = trace2
         self.assertIs(traceback2, traceback1)