Need a max_worker parmaeters to the ThreadPoolExecutor

piphone.py

@@ -47,7 +47,7 @@ application = app = Bottle(autojson=False)
 app.install(SQLitePlugin(dbfile=config['piphone']['db']))
 app.install(JSONPlugin(json_dumps=lambda s: json.dumps(s, cls=PiphoneJSONEncoder)))
 
-threads = concurrent.futures.ThreadPoolExecutor()
+threads = concurrent.futures.ThreadPoolExecutor(max_workers=5)
 loop = asyncio.get_event_loop()
 
 running = False