src/Pure/Thy/thy_info.ML

 fun future_schedule task_graph =
   let
     val tasks = Graph.topological_order task_graph |> map_filter (fn name =>
       (case Graph.get_node task_graph name of Task body => SOME (name, body) | _ => NONE));
 
-    val group = TaskQueue.new_group ();
     fun future (name, body) tab =
       let
+        val group = TaskQueue.new_group ();
         val deps = map_filter (Symtab.lookup tab) (Graph.imm_preds task_graph name);
         val x = Future.future (SOME group) deps true body;
       in (x, Symtab.update (name, Future.task_of x) tab) end;
-
-    val exns = #1 (fold_map future tasks Symtab.empty)
-      |> uninterruptible (fn _ => Future.join_results)
-      |> map_filter Exn.get_exn;
-  in
-    if null exns then ()
-    else raise Exn.EXCEPTIONS (exns, "")
+  in
+    #1 (fold_map future tasks Symtab.empty)
+    |> uninterruptible (fn _ => Future.join_results)
+    |> Exn.release_all
+    |> ignore
   end;
 
 local
 
 fun max_task (name, (Task body, m)) NONE = SOME (name: string, (body, m))

     if m <= 1 then schedule_seq tasks
     else if Multithreading.self_critical () then
      (warning (loader_msg "no multithreading within critical section" []);
       schedule_seq tasks)
     else if ! future_scheduler then future_schedule tasks
-    else
-      (case Schedule.schedule (Int.min (m, n)) next_task tasks of
-        [] => ()
-      | exns => raise Exn.EXCEPTIONS (exns, ""))
+    else ignore (Exn.release_all (map Exn.Exn (Schedule.schedule (Int.min (m, n)) next_task tasks)))
   end;
 
 end;