[Python-checkins] gh-108342: Break ref cycle in SSLSocket._create() exc (#108344)

[gpshead]

https://github.com/python/cpython/commit/64f99350351bc46e016b2286f36ba7cd669b79e3
commit: 64f99350351bc46e016b2286f36ba7cd669b79e3
branch: main
author: Victor Stinner <vstinner at python.org>
committer: gpshead <greg at krypto.org>
date: 2023-08-23T05:26:01Z
summary:

gh-108342: Break ref cycle in SSLSocket._create() exc (#108344)

Explicitly break a reference cycle when SSLSocket._create() raises an
exception. Clear the variable storing the exception, since the
exception traceback contains the variables and so creates a reference
cycle.

This test leak was introduced by the test added for the fix of #108310.

files:
M Lib/ssl.py

diff --git a/Lib/ssl.py b/Lib/ssl.py
index ff363c75e7dfd..c4c5a4ca894ee 100644
--- a/Lib/ssl.py
+++ b/Lib/ssl.py
@@ -1021,7 +1021,11 @@ def _create(cls, sock, server_side=False, do_handshake_on_connect=True,
                     self.close()
                 except OSError:
                     pass
-                raise notconn_pre_handshake_data_error
+                try:
+                    raise notconn_pre_handshake_data_error
+                finally:
+                    # Explicitly break the reference cycle.
+                    notconn_pre_handshake_data_error = None
         else:
             connected = True