_signals.py: Guard against use in non-main thread

1 files changed, 6 insertions, 0 deletions

diff --git a/buildstream/_signals.py b/buildstream/_signals.py
index f1e520d37..0035485a5 100644
--- a/buildstream/_signals.py
+++ b/buildstream/_signals.py
@@ -19,6 +19,7 @@
 import os
 import signal
 import sys
+import threading
 import traceback
 from contextlib import contextmanager, ExitStack
 from collections import deque
@@ -71,6 +72,11 @@ def terminator_handler(signal_, frame):
 def terminator(terminate_func):
     global terminator_stack                   # pylint: disable=global-statement
 
+    # Signal handling only works in the main thread
+    if threading.current_thread() != threading.main_thread():
+        yield
+        return
+
     outermost = False if terminator_stack else True
 
     terminator_stack.append(terminate_func)