Do not call ray init again if ray was already initialized

Author: AnesBenmerzoug

src/pydvl/utils/parallel/backend.py

@@ -136,9 +136,8 @@ def __init__(self, config: ParallelConfig):
         config_dict.pop("backend")
         config_dict["num_cpus"] = config_dict.pop("n_local_workers")
         self.config = config_dict
-        if self.config["address"] is None:
-            self.config["ignore_reinit_error"] = True
-        ray.init(**self.config)
+        if not ray.is_initialized():
+            ray.init(**self.config)
 
     def get(
         self,