From b9c37112a22c2e0e3cc64ec08d643f3b5f9db63f Mon Sep 17 00:00:00 2001
From: Megvii Engine Team <megengine@megvii.com>
Date: Fri, 11 Dec 2020 14:53:38 +0800
Subject: [PATCH] refactor(mge/distributed): skip barrier when running with
 single node

GitOrigin-RevId: 6cd5a2e1e2447b9b41a9b842e2656121aac36308
---
 imperative/python/megengine/distributed/group.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/imperative/python/megengine/distributed/group.py b/imperative/python/megengine/distributed/group.py
index 0461091b..aa52d8f4 100644
--- a/imperative/python/megengine/distributed/group.py
+++ b/imperative/python/megengine/distributed/group.py
@@ -173,5 +173,8 @@ def new_group(proc_ranks: List[int]) -> Group:
 
 def group_barrier(group: Optional[Group] = WORLD) -> None:
     """Block until all ranks in the group reach this barrier."""
+    # if running with single node, skip it
+    if _sd is None:
+        return
     assert isinstance(group, Group)
     _sd.client.group_barrier(group.key, group.size)
-- 
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