Prevent DoS of batch (#3605)

src/clusterfuzz/_internal/bot/tasks/task_types.py

@@ -120,6 +120,16 @@ def preprocess(self, task_argument, job_type, uworker_env):
     return download_url
 
 
+class UTaskCombined(BaseUTask):
+  """Special kind of UTask where tasks are created as utasks and treated as
+  tasks within a batch job. Tasks received on the queue will still execute
+  locally. This should ease the transition to UTask and prevent batch from being
+  DoSed."""
+  def execute(self, task_argument, job_type, uworker_env):
+    self.execute_locally(task_argument, job_type, uworker_env)
+
+
+
 def is_remotely_executing_utasks():
   return (environment.is_production() and
           environment.get_value('REMOTE_UTASK_EXECUTION') and
@@ -177,7 +187,7 @@ def execute(self, task_argument, job_type, uworker_env):
     'unpack': TrustedTask,
     'postprocess': PostprocessTask,
     'uworker_main': UworkerMainTask,
-    'variant': UTaskLocalExecutor,
+    'variant': UTaskCombined,
 }