src/Pure/Tools/build.scala

 
     private val graph_file = Isabelle_System.tmp_file("session_graph", "pdf")
     isabelle.graphview.Graph_File.write(options, graph_file, deps(name).session_graph_display)
 
     private val export_tmp_dir = Isabelle_System.tmp_dir("export")
-    private val export_consumer = Export.consumer(store.open_database(name, output = true))
+    private val export_consumer =
+      Export.consumer(store.open_database(name, output = true), cache = store.xz_cache)
 
     private val future_result: Future[Process_Result] =
       Future.thread("build") {
         val parent = info.parent.getOrElse("")
         val base = deps(name)