From 6eab3ce464e9ff79e4192de4f1c778d3ef89379b Mon Sep 17 00:00:00 2001
From: Matthew Rocklin <mrocklin@gmail.com>
Date: Tue, 21 Jul 2020 08:05:06 -0700
Subject: [PATCH] Iterate over list of comms (#3959)

Previously this list could change during iteration
---
 distributed/core.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/distributed/core.py b/distributed/core.py
index 250ea076e0..16c611142f 100644
--- a/distributed/core.py
+++ b/distributed/core.py
@@ -606,7 +606,7 @@ def close(self):
                 break
             else:
                 yield asyncio.sleep(0.05)
-        yield [comm.close() for comm in self._comms]  # then forcefully close
+        yield [comm.close() for comm in list(self._comms)]  # then forcefully close
         for cb in self._ongoing_coroutines:
             cb.cancel()
         for i in range(10):