Using 'cgroup' in runtime server to limit cpu and memory resources.
Each pod in deployment will has respective 'cgroup' directory on host.
Under '/sys/fs/cgroup/xx/kubepods/<qos_class>/pod<uid>' directory, use
HOSTNAME to create a new cgroup folder, which will only be used to
limit function execution. Then we do not need to care about how and
when to delete this new folder on host.
Use 'openstackqinling/python-runtime:0.0.3' as the new python runtime