# Interview — Senior Java Backend

- **Difficulty**: hard
- **Started**: 2026-04-28T05:28:12.902Z
- **Ended**: 2026-04-28T05:28:17.227Z
- **Target**: 4 questions / 10 min

## Score: 1.0 / 10 — _strong-no-hire_

### Dimensions
- Technical depth: 0/10 — Candidate skipped the only technical question about JVM tuning from G1 to ZGC.
- System design: 0/10 — Candidate did not respond to the system design question for a payment authorization service.
- Communication: 0/10 — Candidate provided no verbal responses throughout the interview.
- Role fit: 1/10 — Resume lists 10 years backend, 5 in fintech, but candidate refused to engage in interview.

### Strengths
- Resume indicates relevant experience: 10 years backend, fintech, Java/Spring Boot, JVM tuning.

### Weaknesses
- Refused to answer the first interview question, providing no technical evidence.
- Did not respond to the system design question, leaving design skills unassessed.
- Overall lack of engagement suggests unwillingness to participate in the interview process.
- No opportunity to evaluate communication or problem-solving skills.
- Cannot verify any of the claims made on the resume.

### Study plan
- [ ] Practice articulating past technical decisions in interview settings, especially JVM tuning choices.
- [ ] Study JVM garbage collection specifics (G1, ZGC) and how to measure latency/throughput improvements.
- [ ] Review system design for high-throughput payment services with idempotency and exactly-once semantics.
- [ ] Develop ability to handle interview pressure and respond to questions even if uncertain.
- [ ] Prepare concrete examples from past work to demonstrate depth and trade-offs.
- [ ] Engage in mock interviews to build comfort with behavioral and technical questioning.

## Transcript

**[0] INTERVIEWER**

Hello, I’m [Your Name], a senior engineer here. Thanks for joining. Let’s start with Java: you mentioned tuning from G1 to ZGC—what specific latency or throughput problem drove that migration, and how did you measure the improvement?

**[1] CANDIDATE**

[skipped — candidate chose not to answer]

**[2] INTERVIEWER**

Understood. Let’s move to system design: design a payment authorization service that must handle 5k TPS with under 100ms p99 latency, using Postgres and Kafka—walk me through the data flow and how you’d avoid duplicate charges during retries.