KafkaIQ

from kafka import KafkaConsumer, TopicPartition import argparse, time, sys def slow_consume(bootstrap, topic, group, sleep_ms, commit_every, max_poll_records): c = KafkaConsumer( topic, bootstrap_servers=bootstrap, group_id=group, enable_auto_commit=False, # we commit manually auto_offset_reset="earliest", # start from beginning on first run max_poll_records=max_poll_records, request_timeout_ms=15000, consumer_timeout_ms=0, # block forever until Ctrl+C ) seen = 0 print(f"Consuming from topic='{topic}', group='{group}' " f"(sleep={sleep_ms}ms/message, commit_every={commit_every})") try: while True: batch = c.poll(timeout_ms=1000, max_records=max_poll_records) total = sum(len(v) for v in batch.values()) if total == 0: continue for tp, recs in batch.items(): for r in recs: # simulate slow processing time.sleep(sleep_ms / 1000.0) seen += 1 if seen % commit_every == 0: c.commit() # sync commit print(f"Committed after {seen} messages") except KeyboardInterrupt: print("\nStopping… committing final offsets") try: c.commit() except Exception: pass c.close() if __name__ == "__main__": ap = argparse.ArgumentParser() ap.add_argument("--bootstrap", default="localhost:9092") ap.add_argument("--topic", default="x-topic") ap.add_argument("--group", default="x-lag-demo") ap.add_argument("--sleep-ms", type=int, default=50) # increase to make lag bigger ap.add_argument("--commit-every", type=int, default=500) # commit less often -> more lag ap.add_argument("--max-poll-records", type=int, default=100) args = ap.parse_args() slow_consume(args.bootstrap, args.topic, args.group, args.sleep_ms, args.commit_every, args.max_poll_records) # python .\consumer.py --topic my-topic --group lag-demo --sleep-ms 50 --commit-every 500 # Consuming from topic='my-topic', group='lag-demo' (sleep=50ms/message, commit_every=500) # Committed after 500 messages # Committed after 1000 messages # Committed after 1500 messages # Committed after 2000 messages # Committed after 2500 messages # Committed after 3000 messages # Committed after 3500 messages # Committed after 4000 messages # Committed after 4500 messages # Committed after 5000 messages