I un-commented the -verbose:gc option in hbase-env.sh, which print out the gc info.
but when I use hbase zkcli to check zk, it can not connect to the server.
the problem is zkcli uses "hbase org.apache.hadoop.hbase.zookeeper.ZooKeeperMainServerArg" to get the server_arg in the script hbase. when gc verbose option is open, the output of ZooKeeperMainServerArg is with gc info, which masses up with server_arg. and this is the reason stop zkcli working.
I think the easiest way to fix this is to trim the gc info out of server_arg in the hbase script.