def start()

in skywalking/agent/__init__.py [0:0]

• 48 lines of code
• 17 McCabe index (conditional complexity)

    def start(self) -> None:
        """
        Start would be called by user or os.register_at_fork() callback
        Start will proceed if and only if the agent is not started in the
        current process.

        When os.fork(), the service instance should be changed to a new one by appending pid.
        """
        loggings.init()

        if sys.version_info < (3, 7):
            # agent may or may not work for Python 3.6 and below
            # since 3.6 is EOL, we will not officially support it
            logger.warning('SkyWalking Python agent does not support Python 3.6 and below, '
                           'please upgrade to Python 3.7 or above.')
        # Below is required for grpcio to work with fork()
        # https://github.com/grpc/grpc/blob/master/doc/fork_support.md
        if config.agent_protocol == 'grpc' and config.agent_experimental_fork_support:
            python_major_version: tuple = sys.version_info[:2]
            if python_major_version == (3, 7):
                logger.warning('gRPC fork support may cause hanging on Python 3.7 '
                               'when used together with gRPC and subprocess lib'
                               'See: https://github.com/grpc/grpc/issues/18075.'
                               'Please consider upgrade to Python 3.8+, '
                               'or use HTTP/Kafka protocol, or disable experimental fork support '
                               'if your application did not start successfully.')

            os.environ['GRPC_ENABLE_FORK_SUPPORT'] = 'true'
            os.environ['GRPC_POLL_STRATEGY'] = 'poll'

        if not self.__started:
            # if not already started, start the agent
            config.finalize()  # Must be finalized exactly once

            self.__started = True
            logger.info(f'SkyWalking agent instance {config.agent_instance_name} starting in pid-{os.getpid()}.')

            # Install log reporter core
            # TODO - Add support for printing traceID/ context in logs
            if config.agent_log_reporter_active:
                from skywalking import log
                log.install()
            # Here we install all other lib plugins on first time start (parent process)
            plugins.install()
        elif self.__started and os.getpid() == self.started_pid:
            # if already started, and this is the same process, raise an error
            raise RuntimeError('SkyWalking Python agent has already been started in this process, '
                               'did you call start more than once in your code + sw-python CLI? '
                               'If you already use sw-python CLI, you should remove the manual start(), vice versa.')
        # Else there's a new process (after fork()), we will restart the agent in the new process

        self.started_pid = os.getpid()

        flag = False
        try:
            from gevent import monkey
            flag = monkey.is_module_patched('socket')
        except ModuleNotFoundError:
            logger.debug("it was found that no gevent was used, if you don't use, please ignore.")
        if flag:
            import grpc.experimental.gevent as grpc_gevent
            grpc_gevent.init_gevent()

        if config.agent_profile_active:
            profile.init()
        if config.agent_meter_reporter_active:
            meter.init(force=True)  # force re-init after fork()

        self.__bootstrap()  # calls init_threading

        atexit.register(self.__fini)

        if config.agent_experimental_fork_support:
            if hasattr(os, 'register_at_fork'):
                os.register_at_fork(before=self.__fork_before, after_in_parent=self.__fork_after_in_parent,
                                    after_in_child=self.__fork_after_in_child)