Linux Process and Service Management Questions

import os, time, threading

CGROUP_PATH = "/sys/fs/cgroup/lowprio"  # cgroup v2
SWAP_THRESHOLD_BYTES = 500*1024*1024
SAMPLE_INTERVAL = 5

def read_swap_and_starttime(pid):
    try:
        with open(f"/proc/{pid}/smaps_rollup") as f:
            data = f.read()
        swap = int(next(line for line in data.splitlines() if line.startswith("Swap:")).split()[1]) * 1024
        with open(f"/proc/{pid}/stat") as f:
            parts = f.read().split()
            start_time = parts[21]  # clock ticks
        return swap, start_time
    except Exception:
        return None, None

def move_to_cgroup(pid, start_time):
    # verify still same process
    cur = read_swap_and_starttime(pid)
    if cur[1] != start_time:
        return False
    try:
        with open(os.path.join(CGROUP_PATH, "cgroup.procs"), "a") as cg:
            cg.write(str(pid)+"\n")
        return True
    except Exception:
        return False

def monitor():
    while True:
        pids = [d for d in os.listdir("/proc") if d.isdigit()]
        for pid in pids:
            swap, start = read_swap_and_starttime(pid)
            if swap and swap > SWAP_THRESHOLD_BYTES:
                threading.Thread(target=move_to_cgroup, args=(pid,start)).start()
        time.sleep(SAMPLE_INTERVAL)

# host-level
free -m; vmstat 1 5; dmesg --ctime | tail -n 200
ps aux --sort=-rss | head -n 10
# container/k8s
docker ps --no-trunc; docker stats --no-stream CONTAINER_ID
kubectl get pods -o wide
kubectl top pod POD -n NS
kubectl describe pod POD -n NS