Please look into an update of the code to use bulk updates for item_rtdata table.  I have 4978181 rows in the item_rtdata table and replication is getting choked out on all the individual "update item_rtdata set state=1,error='xxxxx' where itemid=9689382" statements.  If you create a temporary table like item_rtdata, then just insert into the temp table up to a set limit of 5k rows, then commit an update item_rtdata join temp on item_rtdata.itemid=temp.itemid set item_rtdata.error=temp.error, item_rtdata.state=temp.state, then do the next 5k chunk until all chunks completed for that cycle.  That should speed up many operations of the database activity.