python · miss-islington · Dec 6, 2019 · Dec 6, 2019
diff --git a/Lib/codeop.py b/Lib/codeop.py
@@ -93,10 +93,13 @@ def _maybe_compile(compiler, source, filename, symbol):
    except SyntaxError as e:
        err2 = e

-    if code:
-        return code
-    if not code1 and repr(err1) == repr(err2):
-        raise err1
+    try:
+        if code:
+            return code
+        if not code1 and repr(err1) == repr(err2):
+            raise err1
+    finally:
+        err1 = err2 = None

 def _compile(source, filename, symbol):
    return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT)

diff --git a/Lib/ctypes/macholib/dyld.py b/Lib/ctypes/macholib/dyld.py
@@ -149,6 +149,8 @@ def framework_find(fn, executable_path=None, env=None):
        return dyld_find(fn, executable_path=executable_path, env=env)
    except ValueError:
        raise error
+    finally:
+        error = None

 def test_dyld_find():
    env = {}

diff --git a/Lib/socket.py b/Lib/socket.py
@@ -724,7 +724,11 @@ def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT,
                sock.close()

    if err is not None:
-        raise err
+        try:
+            raise err
+        finally:
+            # Break explicitly a reference cycle
+            err = None
    else:
        raise error("getaddrinfo returns an empty list")


diff --git a/Misc/NEWS.d/next/Library/2019-05-06-15-34-17.bpo-36820.Eh5mIB.rst b/Misc/NEWS.d/next/Library/2019-05-06-15-34-17.bpo-36820.Eh5mIB.rst
@@ -0,0 +1,3 @@
+Break cycle generated when saving an exception in socket.py, codeop.py and
+dyld.py as they keep alive not only the exception but user objects through
+the ``__traceback__`` attribute. Patch by Mario Corchero.