util.xml: Break reference to help the GC (fix #1711) LuaExpat uses a registry reference to track handlers, which makes it so that an upvalue like this creates a reference loop that keeps the parser and its handlers from being garbage collected. The same issue has affected util.xmppstream in the past. Code for checking: local xml_parse = require"util.xml".parse; for i = 1, 10000 do xml_parse("<root/>") end collectgarbage(); collectgarbage(); print(collectgarbage("count"), "KiB"); A future release of LuaExpat may fix the underlying issue there.