concurrent access to interactive args throws error

artiq/language/environment.py

@@ -2,6 +2,7 @@ from collections import OrderedDict
 from inspect import isclass
 from contextlib import contextmanager
 from types import SimpleNamespace
+import threading
 
 from sipyco import pyon
 
@@ -262,6 +263,7 @@ class HasEnvironment:
         self.__in_build = True
         self.build(*args, **kwargs)
         self.__in_build = False
+        self.__interactive_semaphore = threading.Semaphore()
 
     def register_child(self, child):
         self.children.append(child)
@@ -349,7 +351,10 @@ class HasEnvironment:
         namespace.setattr_argument = setattr_argument
         yield namespace
         del namespace.setattr_argument
+        if not self.__interactive_semaphore.acquire(blocking=False):
+            raise RuntimeError("concurrent calls to interactive with the same RID is not supported")
         argdict = self.__argument_mgr.get_interactive(interactive_arglist, title)
+        self.__interactive_semaphore.release()
         for key, value in argdict.items():
             setattr(namespace, key, value)