add find_unused_parameters in fleet init (#3570)

ppdet/engine/env.py

@@ -26,8 +26,10 @@ from paddle.distributed import fleet
 __all__ = ['init_parallel_env', 'set_random_seed', 'init_fleet_env']
 
 
-def init_fleet_env():
-    fleet.init(is_collective=True)
+def init_fleet_env(find_unused_parameters=False):
+    strategy = fleet.DistributedStrategy()
+    strategy.find_unused_parameters = find_unused_parameters
+    fleet.init(is_collective=True, strategy=strategy)
 
 
 def init_parallel_env():

tools/train.py

@@ -90,7 +90,7 @@ def parse_args():
 def run(FLAGS, cfg):
     # init fleet environment
     if cfg.fleet:
-        init_fleet_env()
+        init_fleet_env(cfg.get('find_unused_parameters', False))
     else:
         # init parallel environment if nranks > 1
         init_parallel_env()