From 4d1ef02802cc9742ed93acc367977113ed1aeda2 Mon Sep 17 00:00:00 2001
From: Eric Severance <esev@esev.com>
Date: Tue, 11 Aug 2020 14:20:43 -0700
Subject: [PATCH] Stream clients operate on a copy of the intnernal
 self._outputs dict (#38766)

---
 homeassistant/components/stream/__init__.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/homeassistant/components/stream/__init__.py b/homeassistant/components/stream/__init__.py
index aeab212b78c..520e3047439 100644
--- a/homeassistant/components/stream/__init__.py
+++ b/homeassistant/components/stream/__init__.py
@@ -2,6 +2,7 @@
 import logging
 import secrets
 import threading
+from types import MappingProxyType
 
 import voluptuous as vol
 
@@ -137,8 +138,10 @@ class Stream:
 
     @property
     def outputs(self):
-        """Return stream outputs."""
-        return self._outputs
+        """Return a copy of the stream outputs."""
+        # A copy is returned so the caller can iterate through the outputs
+        # without concern about self._outputs being modified from another thread.
+        return MappingProxyType(self._outputs.copy())
 
     def add_provider(self, fmt):
         """Add provider output stream."""