BankAccount Race Condition (Find & Fix)

Problem Overview

You are given a BankAccount class with a deposit() method, exercised via a ThreadPoolExecutor with 2 workers submitting two concurrent deposits (e.g., 500 and 700). The deposit() implementation has a deliberate race condition: it reads self.balance, sleeps ~0.1s, then writes self.balance = self.balance + amount — so both threads read…

• 3 candidate-reported follow-ups — the exact probes interviewers asked, with the trigger for each
• The rest of the problem statement — full requirements, constraints, and edge cases
• Approach and trade-offs — what passing candidates did, and the mistakes that sink people