src/Pure/Tools/build_job.scala

           }
         }
 
       val process_result =
         Isabelle_Thread.interrupt_handler(_ => process.terminate) { process.await_shutdown }
+
+      session.stop()
 
       val export_errors =
         export_consumer.shutdown(close = true).map(Output.error_message_text)
 
       val document_errors =