Hello, I'm trying to process results from several Deferreds (d1, d2) with DeferredList, merging it into one list and sending back to client. While merging works, the client has no results. What is the way to do tasks (db queries in my case) in parallel and then merge results? BTW, are nested runInteraction ok? Thanks for help! Pet class Test: def __init__(self, cursor): self.cursor = cursor def test(db, params): if params.get('query'): params['q'] = self.someFunc3(db, params) def processResults(results, out): #merge results into one for _, r in results: out.extend(r) return out out = [] d1 = self.cursor.runInteraction(self.someFunc, params) d2 = self.cursor.runInteraction(self.someFunc2, params) d = DeferredList([d1,d2]) d.addCallback(processResults, out) d.addErrback(log.err) return d class XMLRPCProtokoll(xmlrpc.XMLRPC): def __init__(self): self.db = adbapi.ConnectionPool() xmlrpc.XMLRPC.__init__(self, True) def xmlrpc_test(self, param): t = Test(self.db) return self.db.runInteraction(t.test, param)