There is something wrong about the network of my lab, then the emerge --sync can't suceed. I noticed that rsync freezed at receiving file list, but it didn't in fact and it just didn't print the process of receiving the file list. This is a change in emerge system. You can enable the original act of rsync by adding this line to your /etc/make.conf:
PORTAGE_RSYNC_EXTRA_OPTS = "--progress" -- Wang ShaoChun(王绍春) <[EMAIL PROTECTED]> -- gentoo-user@gentoo.org mailing list