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annotate asyncio_threads/bank_question/main.py @ 71:75de5903355c

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Giagantic changes that update Dowa library to be more align with stb style array and hashmap. Updated Seobeo to be caching on server side instead of file level caching. Deleted bunch of things I don't really use.
author June Park <parkjune1995@gmail.com>
date Sun, 28 Dec 2025 20:34:22 -0800
parents 46daba6e3cf4
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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46daba6e3cf4 Few python scrtips to show how to use asychio.
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1 # # Bank Account
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2 #
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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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4 #
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5 # Task
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6 #
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7 # Identify the concurrency bugs in the implementation.
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8 #
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9 # Explain why these bugs occur.
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10 #
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11 # Fix the implementation without modifying the existing BankAccount class directly.
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12 #
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13 # You may use subclassing (Python) or embedding (Go-style composition), depending on the language you choose.
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14 #
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15 # Ensure your solution is thread-safe and produces the correct final balance (1200).
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16
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17 from threading import Lock
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18 from concurrent.futures import ThreadPoolExecutor
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19 import time
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20
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21 class BankAccount:
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22 def __init__(self, balance):
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23 self.balance = balance
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24 self._lock = Lock()
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25
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26 def deposit(self, amount):
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27 while (self._lock.locked()):
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28 pass
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29 self._lock.acquire()
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30 new_balance = self.balance + amount # read
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31 time.sleep(0.1) # simulate delay
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32 self.balance = new_balance # write
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33 self._lock.release()
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34
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36 account = BankAccount(0)
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37
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38 with ThreadPoolExecutor(max_workers=2) as executor:
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39 futures = [
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40 executor.submit(account.deposit, 500),
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41 executor.submit(account.deposit, 700),
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42 ]
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43 print(account.balance)