Make shutdown flag atomic

Rafał Hibner · zanmato1984 · commit 6da4957e4e3d · 2025-09-19T10:14:50.000-07:00
diff --git a/cpp/src/arrow/acero/concurrent_queue_internal.h b/cpp/src/arrow/acero/concurrent_queue_internal.h
@@ -175,7 +175,7 @@ class BackpressureConcurrentQueue : private ConcurrentQueue<T> {
 
  private:
   BackpressureHandler handler_;
-  bool shutdown_{false};
+  std::atomic<bool> shutdown_{false};
 };
 
 }  // namespace arrow::acero
