[Dygraph] Fix barrier bugs of ProcessGroup in Eager Mode (#43589)

* fix pg bugs

* update

python/paddle/distributed/collective.py

@@ -378,6 +378,7 @@ def new_group(ranks=None, backend=None):
         _group_map_by_name[group_name] = group
         _group_map[gid] = group
 
+        paddle.distributed.barrier(group=group)
         return group
 
     if not backend:

python/paddle/distributed/parallel.py

@@ -20,6 +20,7 @@ from multiprocessing import Manager  # noqa: F401
 import time
 import sys
 
+import paddle
 from paddle import compat as cpt
 
 # deprecated module import
@@ -253,6 +254,7 @@ def init_parallel_env():
         _set_group_map_by_name(_default_group_name, group)
         _set_group_map(0, group)
         parallel_helper._set_parallel_ctx(True)
+        paddle.distributed.barrier(group=group)
         return group
 
     node_num = set([i.split(":")[0] for i in parallel_env.trainer_endpoints])