Issue #23865: close() methods in multiple modules now are idempotent and more

robust at shutdown. If needs to release multiple resources, they are released
even if errors are occured.

1 files changed, 8 insertions, 4 deletions

diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 2eee76c..4e42ad2 100644
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -722,10 +722,14 @@ class _singlefileMailbox(Mailbox):
 
     def close(self):
         """Flush and close the mailbox."""
-        self.flush()
-        if self._locked:
-            self.unlock()
-        self._file.close()  # Sync has been done by self.flush() above.
+        try:
+            self.flush()
+        finally:
+            try:
+                if self._locked:
+                    self.unlock()
+            finally:
+                self._file.close()  # Sync has been done by self.flush() above.
 
     def _lookup(self, key=None):
         """Return (start, stop) or raise KeyError."""