Deadlock on wallet transfers
MySQL/InnoDB. After a feature deploy enabling a new 'transfer between two wallets' endpoint, error logs fill with `Deadlock found when trying to get lock; try restarting transaction` during peak traffic. It only happens when two transfers involve the same pair of wallets in opposite directions. Throughput is fine otherwise; the endpoint occasionally 500s. Triage, mitigate, and give the correct durable fix.
What a strong answer looks like
Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.
0:00 of about 30 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.