Confluent - Interview Experience - Software Engineer
Confluent - Interview Experience - Software Engineer
Result: Offer Number of Rounds: 4
Got an offer from Confluent after 4 rounds. Question bank is small and forum coverage helped a lot, so figured I'd add to it.
Round 1 coding: tail -n implementation. The twist is streaming to stdout without loading the full file into memory. They give you a file API: read N bytes, move pointer forward/backward, get file size. Went with the offset-from-end approach using file size and pointer arithmetic. Interviewer was engaged, we talked through the buffer tradeoff.
Round 2 coding: Sensor health / wasAlive problem. Given (sensorID, timestamp) pairs, implement wasAlive(sensorID, startTime). Basically if a sensor goes quiet for 3 consecutive 100ms slots it's considered down. Solved it cleanly, added binary search for the follow-up. Wasn't too bad once I saw the pattern.
System design round 1: RSS feed aggregator. REST vs RPC discussion, multi-client support (mobile vs web). Pretty standard.
System design round 2: Temporary email system at 100M users. Tricky part is generating human-like usernames to avoid spam filters, plus fast dedup. Discussed bloom filter for the initial lookup before hitting the DB. Interviewer here was really into it, best discussion of the day tbh.
Two weeks from onsite to offer. Process was smooth, interviewers actually knew what they were talking about. Would recommend if you're prepping for streaming/infra roles.
Replies (4)
how hard was the temp email system round? that one looks tricky from what I've read on the forums
definitely the hardest one. bloom filter discussion took most of the time. know your tradeoffs going in
tail -n comes up so often. did they specify memory constraints upfront or did you have to ask?
congrats! was the wasAlive window size fixed at 500ms or configurable?
5 slots x 100ms each. fixed for my round. 3 consecutive inactive = down
small question bank cuts both ways lol. easy to prep but they know you prepped