Function build_cgroup_stream_script 

pub fn build_cgroup_stream_script() -> String

In-container loop of the long-lived sampler exec (issue #242): $1 is the cgroup directory. The host paces it with one newline per interval on stdin (docker exec -i), so it runs only shell builtins: the task’s own CPU limit pays for no cat, sed or sleep processes. Stdin reaches EOF when the exec’s client is gone, so the loop never outlives the sampler; dockerd would accept its output even then. Exit 3: unreadable counters (no delegated memory controller), which no later round can change.