chore: only spawn exex manager if there are exex's

crates/node-builder/src/builder.rs

@@ -603,24 +603,26 @@ where
         }
 
         // spawn exex manager
-        // todo(onbjerg): rm magic number
-        debug!(target: "reth::cli", "spawning exex manager");
-        let exex_manager = ExExManager::new(exex_handles, 1024);
-        let exex_manager_handle = exex_manager.handle();
-        ctx.executor.spawn_critical("exex manager", async move {
-            exex_manager.await.expect("exex manager crashed");
-        });
+        if !exex_handles.is_empty() {
+            debug!(target: "reth::cli", "spawning exex manager");
+            // todo(onbjerg): rm magic number
+            let exex_manager = ExExManager::new(exex_handles, 1024);
+            let exex_manager_handle = exex_manager.handle();
+            ctx.executor.spawn_critical("exex manager", async move {
+                exex_manager.await.expect("exex manager crashed");
+            });
 
-        // send notifications from the blockchain tree to exex manager
-        let mut canon_state_notifications = blockchain_tree.subscribe_to_canonical_state();
-        ctx.executor.spawn_critical("exex manager blockchain tree notifications", async move {
-            while let Ok(notification) = canon_state_notifications.recv().await {
-                exex_manager_handle
-                    .send_async(notification)
-                    .await
-                    .expect("blockchain tree notification could not be sent to exex manager");
-            }
-        });
+            // send notifications from the blockchain tree to exex manager
+            let mut canon_state_notifications = blockchain_tree.subscribe_to_canonical_state();
+            ctx.executor.spawn_critical("exex manager blockchain tree notifications", async move {
+                while let Ok(notification) = canon_state_notifications.recv().await {
+                    exex_manager_handle
+                        .send_async(notification)
+                        .await
+                        .expect("blockchain tree notification could not be sent to exex manager");
+                }
+            });
+        }
 
         let BuilderContext {
             provider: blockchain_db,