def populate_menv(menv, agent_cls_name, log_folder):
    '''Populate given multiprocessing grid environment with agents.

    :param menv: Instance of :py:class:`GridMultiEnvironment`
    :param str agent_cls_name: Name of the agent class, e.g. 'grip_mp:GridAgent'
    :param str log_folder: Root logging folder for the agents.
    '''
    gs = menv.gs
    n_agents = gs[0] * gs[1]
    n_slaves = len(menv.addrs)
    logger.info("Populating {} with {} agents".format(HOST, n_agents*n_slaves))
    run(menv.populate(agent_cls_name, n_agents, log_folder=log_folder))
    logger.info("Populating complete.")