Avoid stacktrace on process exit in Client.__del__() (#3397)

Client.close() may call ConnectionPool.release() or
ConnectionPool.disconnect(); both methods may end up calling
os.getpid() (through ConnectionPool._checkpid() or threading.Lock()
(through ConnectionPool.reset()). As mentioned in the Python
documentation [1], at interpreter shutdown, module globals (in this
case, the os and threading module references) may be deleted or set to
None before __del__() methods are called. This causes an
AttributeError to be raised when trying to run e.g. os.getpid(); while
the error is ignored by the interpreter, the traceback is still
printed out to stderr.

Closes #3014

[1] https://docs.python.org/3/reference/datamodel.html#object.__del__

Co-authored-by: petyaslavova <[email protected]>

Author: noirbee

redis/client.py

@@ -570,7 +570,10 @@ def __exit__(self, exc_type, exc_value, traceback):
         self.close()
 
     def __del__(self):
-        self.close()
+        try:
+            self.close()
+        except Exception:
+            pass
 
     def close(self) -> None:
         # In case a connection property does not yet exist

redis/cluster.py

@@ -663,7 +663,10 @@ def __exit__(self, exc_type, exc_value, traceback):
         self.close()
 
     def __del__(self):
-        self.close()
+        try:
+            self.close()
+        except Exception:
+            pass
 
     def disconnect_connection_pools(self):
         for node in self.get_nodes():