def find_orphaned_instances(xenapi):
    """Find and return a list of orphaned instances."""
    ctxt = context.get_admin_context(read_deleted="only")

    orphaned_instances = []

    for vm_ref, vm_rec in _get_applicable_vm_recs(xenapi):
        try:
            uuid = vm_rec['other_config']['nova_uuid']
            instance = db.instance_get_by_uuid(ctxt, uuid)
        except (__HOLE__, exception.InstanceNotFound):
            # NOTE(jk0): Err on the side of caution here. If we don't know
            # anything about the particular instance, ignore it.
            print_xen_object("INFO: Ignoring VM", vm_rec, indent_level=0)
            continue

        # NOTE(jk0): This would be triggered if a VM was deleted but the
        # actual deletion process failed somewhere along the line.
        is_active_and_deleting = (instance.vm_state == "active" and
                instance.task_state == "deleting")

        # NOTE(jk0): A zombie VM is an instance that is not active and hasn't
        # been updated in over the specified period.
        is_zombie_vm = (instance.vm_state != "active"
                and timeutils.is_older_than(instance.updated_at,
                        CONF.zombie_instance_updated_at_window))

        if is_active_and_deleting or is_zombie_vm:
            orphaned_instances.append((vm_ref, vm_rec, instance))

    return orphaned_instances
dataset/ETHPy150Open openstack/nova/tools/xenserver/vm_vdi_cleaner.py/find_orphaned_instances