From b1c06b4d87c5e0bf7482e33a898ede2ef0085ebf Mon Sep 17 00:00:00 2001
From: Nick Macholl <nick@databento.com>
Date: Thu, 15 Aug 2024 15:31:31 -0700
Subject: [PATCH] FIX: Fix multiple calls to start live thread

---
 CHANGELOG.md             | 1 +
 databento/live/client.py | 6 ++++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 496be0b..962fc68 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 
 #### Bug fixes
 - Fixed an issue receiving multiple DBN v1 `ErrorMsg` in the `Live` client would cause an `InvalidState` error
+- Fixed an issue where creating `Live` clients in multiple threads could cause a `RuntimeError` upon initialization
 
 ## 0.39.2 - 2024-08-13
 
diff --git a/databento/live/client.py b/databento/live/client.py
index 224984b..978b867 100644
--- a/databento/live/client.py
+++ b/databento/live/client.py
@@ -61,6 +61,7 @@ class Live:
     """
 
     _loop = asyncio.new_event_loop()
+    _lock = threading.Lock()
     _thread = threading.Thread(
         target=_loop.run_forever,
         name="databento_live",
@@ -109,8 +110,9 @@ def __init__(
 
         self._session._user_callbacks.append((self._map_symbol, None))
 
-        if not Live._thread.is_alive():
-            Live._thread.start()
+        with Live._lock:
+            if not Live._thread.is_alive():
+                Live._thread.start()
 
     def __del__(self) -> None:
         try: