Set 'GRPC_FAIL_FAST' to 'user_caller' in MultiProcessCluster.

PiperOrigin-RevId: 338147299
Change-Id: I3b8bdcbfe5d57fcd630dd69a138d07756bef0a82

tensorflow/python/distribute/multi_worker_test_base.py

@@ -234,6 +234,11 @@ class MultiProcessCluster(object):
       server_config = config_pb2.ConfigProto()
       server_config.device_count['GPU'] = 0
 
+      # Set the environment variable to prevent hanging upon job failure and
+      # restart. Note that it defaults to 'use_caller' at Google, but defaults
+      # to False in OSS.
+      os.environ['GRPC_FAIL_FAST'] = 'use_caller'
+
       server_lib.Server(
           cluster_spec,
           job_name=task_type,