def __init__()

in gym3/subproc.py [0:0]

• 40 lines of code
• 7 McCabe index (conditional complexity)

    def __init__(self, env_fn, env_kwargs=None, daemon=True):
        if env_kwargs is None:
            env_kwargs = {}
        # tensorflow is not fork safe, and fork doesn't work on all platforms anyway
        self._ctx = mp.get_context("spawn")
        self._p2c, c2p = self._ctx.Pipe()

        # pickle cannot pickle functions, so fallback to cloudpickle if pickle fails
        last_err = None
        for codec, (encode, decode) in CODECS.items():
            try:
                env_fn_serialized = encode(env_fn)
                env_kwargs_serialized = encode(env_kwargs)
            except Exception as e:
                last_err = e
            else:
                break
        else:
            raise Exception(
                f"all attempted encoders failed, tried: {', '.join(CODECS.keys())}.  Last error was:\n  {last_err}.\n\nIf you are pickling a function defined inside of another function, try `pip install cloudpickle` to enable cloudpickle encoding"
            )

        self._child = self._ctx.Process(
            target=_worker,
            kwargs=dict(
                decode=decode,
                env_fn_serialized=env_fn_serialized,
                env_kwargs_serialized=env_kwargs_serialized,
                p2c=self._p2c,
                c2p=c2p,
            ),
            daemon=daemon,
        )
        # clear mpi vars to avoid issues with MPI_init being called in subprocesses
        with _clear_mpi_env_vars():
            self._child.start()
        # close child connection to avoid hangs when child exits unexpectedly
        c2p.close()
        result, err = self._communicate(self._p2c.recv)
        if err is not None:
            self.close()
            raise SubprocError("failed to create env in subprocess") from Exception(
                "exception in subprocess:\n\n" + err
            )
        ob_space, ac_space, num = result
        super().__init__(ob_space=ob_space, ac_space=ac_space, num=num)