get_or_set(): use read replica when reading values

redis_cache/backends/base.py

@@ -455,8 +455,10 @@ class BaseRedisCache(BaseCache):
         lock_key = "__lock__" + key
         fresh_key = "__fresh__" + key
 
-        is_fresh = self._get(client, fresh_key)
-        value = self._get(client, key)
+        read_client = self.get_client(fresh_key, write=False)
+        is_fresh = self._get(read_client, fresh_key)  # use read client
+        read_client = self.get_client(key, write=False)
+        value = self._get(read_client, key)  # use read client
 
         if is_fresh:
             return value