gh-58956: Fix a frame refleak in bdb (#128190)

diff --git a/Lib/bdb.py b/Lib/bdb.py
index 81bba8a130f97c3bf54d8b305b22460c23b58a4f..73e249621a053be753e8b5ccb13541b50d68a188 100644 (file)
--- a/Lib/bdb.py
+++ b/Lib/bdb.py
@@ -404,6 +404,7 @@ class Bdb:
             frame.f_trace_lines = True
             frame = frame.f_back
         self.set_stepinstr()
+        self.enterframe = None
         sys.settrace(self.trace_dispatch)
 
     def set_continue(self):
@@ -423,6 +424,7 @@ class Bdb:
             for frame, (trace_lines, trace_opcodes) in self.frame_trace_lines_opcodes.items():
                 frame.f_trace_lines, frame.f_trace_opcodes = trace_lines, trace_opcodes
             self.frame_trace_lines_opcodes = {}
+            self.enterframe = None
 
     def set_quit(self):
         """Set quitting attribute to True.

diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py
index ace5544f4106d09869df29da03496f1d5f39ec5a..09601623b29ac1692cdd49a76f54cc0505c477b3 100644 (file)
--- a/Lib/test/test_pdb.py
+++ b/Lib/test/test_pdb.py
@@ -3009,6 +3009,57 @@ def test_pdb_f_trace_lines():
     (Pdb) continue
     """
 
+def test_pdb_frame_refleak():
+    """
+    pdb should not leak reference to frames
+
+    >>> def frame_leaker(container):
+    ...     import sys
+    ...     container.append(sys._getframe())
+    ...     import pdb; pdb.Pdb(nosigint=True, readrc=False).set_trace()
+    ...     pass
+
+    >>> def test_function():
+    ...     import gc
+    ...     container = []
+    ...     frame_leaker(container)  # c
+    ...     print(len(gc.get_referrers(container[0])))
+    ...     container = []
+    ...     frame_leaker(container)  # n c
+    ...     print(len(gc.get_referrers(container[0])))
+    ...     container = []
+    ...     frame_leaker(container)  # r c
+    ...     print(len(gc.get_referrers(container[0])))
+
+    >>> with PdbTestInput([  # doctest: +NORMALIZE_WHITESPACE
+    ...     'continue',
+    ...     'next',
+    ...     'continue',
+    ...     'return',
+    ...     'continue',
+    ... ]):
+    ...    test_function()
+    > <doctest test.test_pdb.test_pdb_frame_refleak[0]>(4)frame_leaker()
+    -> import pdb; pdb.Pdb(nosigint=True, readrc=False).set_trace()
+    (Pdb) continue
+    1
+    > <doctest test.test_pdb.test_pdb_frame_refleak[0]>(4)frame_leaker()
+    -> import pdb; pdb.Pdb(nosigint=True, readrc=False).set_trace()
+    (Pdb) next
+    > <doctest test.test_pdb.test_pdb_frame_refleak[0]>(5)frame_leaker()
+    -> pass
+    (Pdb) continue
+    1
+    > <doctest test.test_pdb.test_pdb_frame_refleak[0]>(4)frame_leaker()
+    -> import pdb; pdb.Pdb(nosigint=True, readrc=False).set_trace()
+    (Pdb) return
+    --Return--
+    > <doctest test.test_pdb.test_pdb_frame_refleak[0]>(5)frame_leaker()->None
+    -> pass
+    (Pdb) continue
+    1
+    """
+
 def test_pdb_function_break():
     """Testing the line number of break on function
 

diff --git a/Misc/NEWS.d/next/Library/2024-12-23-02-09-44.gh-issue-58956.4OdMdT.rst b/Misc/NEWS.d/next/Library/2024-12-23-02-09-44.gh-issue-58956.4OdMdT.rst
new file mode 100644 (file)
index 0000000..b78bc5a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-12-23-02-09-44.gh-issue-58956.4OdMdT.rst
@@ -0,0 +1 @@
+Fixed a frame reference leak in :mod:`bdb`.