--- a/src/luan/modules/lucene/Lucene.luan	Thu Jul 11 23:30:55 2019 -0600
+++ b/src/luan/modules/lucene/Lucene.luan	Sun Jul 14 00:43:45 2019 -0600
@@ -12,7 +12,8 @@
 local matches = String.matches or error()
 local Thread = require "luan:Thread.luan"
 local schedule = Thread.schedule or error()
-local run_for_backup = Thread.run_for_backup or error()
+local run_in_lock = Thread.run_in_lock or error()
+local backup_read_lock = Thread.backup_read_lock or error()
 local Time = require "luan:Time.luan"
 local Rpc = require "luan:Rpc.luan"
 local LuceneIndex = require "java:luan.modules.lucene.LuceneIndex"
@@ -141,10 +142,8 @@
 		local lucene_dir = index.dir
 		local function backup()
 			if backup_dir.last_modified() < lucene_dir.last_modified() then
-				run_for_backup(function()
-					index.backup_to(backup_dir)
-					logger.info "backup"
-				end)
+				run_in_lock(backup_read_lock, index.backup_to,backup_dir)
+				logger.info "backup"
 			end
 		end
 		schedule( backup, {