[swift] Openstack controller/keystone cause not uploading file to swift storage

Hi, I've installed swift storage and swift-proxy and keystone for object storage I'm using memcached for caching keystone's data But suddenly in some moments my cpu of keystone servers goes up till 50% (it is apache and keystone proccess) and the swift proxies wouldn't upload anything!!! As I said servers have free cpu and ram and kernel tuned well which parameter should I check for my problem? How can I solve this strange problem?