def get_available_backends(namespace, invoke_on_load=False):
    """
    Return names of the available / installed backends.

    :rtype: ``list`` of ``str``
    """
    # NOTE: We use lazy import because importing from stevedore adds significat import time
    # overhead to other modules which don't need this package (stevedore needs to inspect various
    # entrypoint files on disk for all the installed Python packages which is slow)
    from stevedore.extension import ExtensionManager

    manager = ExtensionManager(namespace=namespace, invoke_on_load=invoke_on_load)
    return manager.names()

    Return names of the available / installed backends.

    :rtype: ``list`` of ``str``
    
st2common/st2common/util/driver_loader.py