Comment 1 for bug 1620971

i think this is problem:
in tacker/cmd/server.py
tacker_api = service.serve_wsgi(service.TackerApiService)
launcher = common_service.launch(cfg.CONF, tacker_api,
                                workers=cfg.CONF.api_workers or None)

in tacker/wsgi.py
self._launcher = common_service.ProcessLauncher(CONF,wait_interval=1.0)
self._server = WorkerService(self, application)
self._launcher.launch_service(self._server, workers=workers)

they both launch sevice with multi workers.
if i remove workers in server.py, it will works.
launcher = common_service.launch(cfg.CONF, tacker_api)