From a1efd4d56d23dae41f5f2457782806a6845179a6 Mon Sep 17 00:00:00 2001
From: Megvii Engine Team <megengine@megvii.com>
Date: Mon, 9 Nov 2020 15:33:52 +0800
Subject: [PATCH] fix(mge/parampack): fix param pack when no param left

GitOrigin-RevId: b88b87606411cb7bae598dcd4792014cad6dbd81
---
 imperative/python/megengine/distributed/helper.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/imperative/python/megengine/distributed/helper.py b/imperative/python/megengine/distributed/helper.py
index 79be16e10..0755ea2ce 100644
--- a/imperative/python/megengine/distributed/helper.py
+++ b/imperative/python/megengine/distributed/helper.py
@@ -211,6 +211,8 @@ class AllreduceCallback:
         self._grad_origin_device = dict()
 
     def _pack(self, dtype):
+        if len(self._packing_list[dtype]) == 0:
+            return
         grad_list = [self._gradients_dict[p] for p in self._packing_list[dtype]]
         shapes = [p.shape for p in self._packing_list[dtype]]
         reduced_grads = pack_allreduce_split(
-- 
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