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[MrJuneJune] Created separate target for generating html from md.
author MrJuneJune <me@mrjunejune.com>
date Mon, 19 Jan 2026 17:33:18 -0800
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1 # Bank Account
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3 You are given a simplified multi-threaded “bank account” implementation used by one of our infrastructure teams. The current code processes deposits concurrently but produces incorrect results.
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5 ```
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6 class BankAccount:
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7 def __init__(self, balance):
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8 self.balance = balance
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10 def deposit(self, amount):
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11 new_balance = self.balance + amount # read
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12 time.sleep(0.1) # simulate delay
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13 self.balance = new_balance # write
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15 account = BankAccount(0)
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17 with ThreadPoolExecutor(max_workers=2) as executor:
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18 futures = [
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19 executor.submit(account.deposit, 500),
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20 executor.submit(account.deposit, 700),
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21 ]
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22 ```
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24 Task
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26 Identify the concurrency bugs in the implementation.
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28 Explain why these bugs occur.
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30 Fix the implementation without modifying the existing BankAccount class directly.
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32 You may use subclassing (Python) or embedding (Go-style composition), depending on the language you choose.
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34 Ensure your solution is thread-safe and produces the correct final balance (1200).