Deep Dive into Complex System or Project Questions

# pseudocode / outline
import time
from collections import defaultdict, deque
import heapq

BUCKET_SECONDS = 60
WINDOW_BUCKETS = 24*60  # 24 hours of 1-min buckets

# in-memory ring of dicts; for production, use Redis/hbase etc.
buckets = deque([defaultdict(lambda: [0,0]) for _ in range(WINDOW_BUCKETS)])  # [requests, errors]

def parse_log(line):
    # extract endpoint and status_code
    return endpoint, int(status_code)

def process_stream(stream):
    current_bucket_idx = int(time.time() // BUCKET_SECONDS) % WINDOW_BUCKETS
    last_bucket_start = int(time.time() // BUCKET_SECONDS) * BUCKET_SECONDS

    for line in stream:
        endpoint, status = parse_log(line)
        now = time.time()
        bucket_idx = int(now // BUCKET_SECONDS) % WINDOW_BUCKETS
        if bucket_idx != current_bucket_idx:
            # rotate buckets for each minute passed
            steps = (bucket_idx - current_bucket_idx) % WINDOW_BUCKETS
            for _ in range(steps):
                buckets.popleft()
                buckets.append(defaultdict(lambda: [0,0]))
            current_bucket_idx = bucket_idx

        b = buckets[-1]  # current minute
        b[endpoint][0] += 1
        if status >= 500 or status >= 400:  # define "error"
            b[endpoint][1] += 1

def compute_top10():
    # aggregate across window
    agg = defaultdict(lambda: [0,0])
    for b in buckets:
        for ep,(req,err) in b.items():
            agg[ep][0] += req
            agg[ep][1] += err

    heap = []
    for ep,(req,err) in agg.items():
        if req >= 1000:  # only compute rate per 1000 reqs
            rate_per_1000 = (err / req) * 1000
            heapq.heappush(heap, (-rate_per_1000, ep, req, err))
    top10 = [heapq.heappop(heap) for _ in range(min(10, len(heap)))]
    return [(ep, -score, req, err) for score,ep,req,err in top10]

apiVersion: v1
kind: LimitRange
spec:
  limits:
  - type: Container
    defaultRequest:
      cpu: "100m"
      memory: "128Mi"
    default:
      cpu: "500m"
      memory: "512Mi"