There are multiply processes of chef_client_run.sh in client nodes

I tried to deploy an openstack cluster with Compass and the progress was hung on the 95%. Ssh to the hanging server n142, checked chef-client process and found multiply processes of chef_client_run.sh.

Here is the result:
[root@test-n142 ~]# ps -ef|grep chef
root 3111 3110 0 Nov26 ? 00:00:03 /bin/bash /etc/chef/chef_client_run.sh
root 4643 4642 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
root 5337 5334 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
root 7294 7293 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
root 8433 8432 0 Nov26 ? 00:00:03 /bin/bash /etc/chef/chef_client_run.sh
root 14551 3111 4 08:13 ? 00:00:00 /opt/chef/embedded/bin/ruby /usr/bin/chef-client --node-name test-n142.demo-cluster -j /etc/chef/test-n142.demo-cluster.json --client_key /etc/chef/test-n142.demo-cluster.pem -L /var/log/chef/test-n142.demo-cluster/chef-client.log
root 14626 14551 20 08:13 ? 00:00:03 chef-client worker: ppid=14551;start=08:13:24;
root 14848 13058 0 08:13 pts/0 00:00:00 grep chef
root 15363 15362 0 Nov26 ? 00:00:03 /bin/bash /etc/chef/chef_client_run.sh
root 15525 15524 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
root 15964 15963 0 Nov26 ? 00:00:03 /bin/bash /etc/chef/chef_client_run.sh
root 16564 16563 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
root 17290 17289 0 Nov26 ? 00:00:03 /bin/bash /etc/chef/chef_client_run.sh
root 20445 20444 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
root 21509 21508 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
root 21968 21967 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
root 29012 29011 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
root 30389 30388 0 Nov26 ? 00:00:02 /bin/bash /etc/chef/chef_client_run.sh
[root@test-n142 ~]#

We should not allow multiply processes of chef_client_run.sh running in the same time.