Final QA (#595)

thread-safety-locks/bank_barrier.py

@@ -6,16 +6,20 @@
 teller_barrier = threading.Barrier(3)
 
 
+def now():
+    return time.strftime("%H:%M:%S")
+
+
 def prepare_for_work(name):
-    print(f"{int(time.time())}: {name} is preparing their counter.")
+    print(f"{now()}: {name} is preparing their counter.")
 
     # Simulate the delay to prepare the counter
     time.sleep(random.randint(1, 3))
-    print(f"{int(time.time())}: {name} has finished preparing.")
+    print(f"{now()}: {name} has finished preparing.")
 
     # Wait for all tellers to finish preparing
     teller_barrier.wait()
-    print(f"{int(time.time())}: {name} is now ready to serve customers.")
+    print(f"{now()}: {name} is now ready to serve customers.")
 
 
 tellers = ["Teller 1", "Teller 2", "Teller 3"]
@@ -24,4 +28,4 @@ def prepare_for_work(name):
     for teller_name in tellers:
         executor.submit(prepare_for_work, teller_name)
 
-print(f"{int(time.time())}: All tellers are ready to serve customers.")
+print(f"{now()}: All tellers are ready to serve customers.")

thread-safety-locks/bank_condition.py

@@ -9,26 +9,30 @@
 customer_queue = []
 
 
+def now():
+    return time.strftime("%H:%M:%S")
+
+
 def serve_customers():
     while True:
         with customer_available_condition:
             # Wait for a customer to arrive
             while not customer_queue:
-                print(f"{int(time.time())}: Teller is waiting for a customer.")
+                print(f"{now()}: Teller is waiting for a customer.")
                 customer_available_condition.wait()
 
             # Serve the customer
             customer = customer_queue.pop(0)
-            print(f"{int(time.time())}: Teller is serving {customer}.")
+            print(f"{now()}: Teller is serving {customer}.")
 
         # Simulate the time taken to serve the customer
-        time.sleep(random.randint(1, 3))
-        print(f"{int(time.time())}: Teller has finished serving {customer}.")
+        time.sleep(random.randint(1, 5))
+        print(f"{now()}: Teller has finished serving {customer}.")
 
 
 def add_customer_to_queue(name):
     with customer_available_condition:
-        print(f"{int(time.time())}: {name} has arrived at the bank.")
+        print(f"{now()}: {name} has arrived at the bank.")
         customer_queue.append(name)
 
         customer_available_condition.notify()
@@ -43,11 +47,8 @@ def add_customer_to_queue(name):
 ]
 
 with ThreadPoolExecutor(max_workers=6) as executor:
-
     teller_thread = executor.submit(serve_customers)
-
     for name in customer_names:
         # Simulate customers arriving at random intervals
-        time.sleep(random.randint(2, 5))
-
+        time.sleep(random.randint(1, 3))
         executor.submit(add_customer_to_queue, name)

thread-safety-locks/bank_deadlock.py

@@ -11,7 +11,7 @@ def __init__(self):
     def deposit(self, amount):
         print(
             f"Thread {threading.current_thread().name} waiting "
-            f"to acquire lock for deposit()"
+            "to acquire lock for deposit()"
         )
         with self.lock:
             print(
@@ -24,7 +24,7 @@ def deposit(self, amount):
     def _update_balance(self, amount):
         print(
             f"Thread {threading.current_thread().name} waiting to acquire "
-            f"lock for _update_balance()"
+            "lock for _update_balance()"
         )
         with self.lock:  # This will cause a deadlock
             print(
@@ -36,16 +36,11 @@ def _update_balance(self, amount):
 
 account = BankAccount()
 
-
-def make_deposit():
-    account.deposit(100)
-
-
 with ThreadPoolExecutor(
     max_workers=3, thread_name_prefix="Worker"
 ) as executor:
     for _ in range(3):
-        executor.submit(make_deposit)
+        executor.submit(account.deposit, 100)
 
 
 print(f"Final balance: {account.balance}")

thread-safety-locks/bank_multithreaded_withdrawal.py

@@ -12,7 +12,7 @@ def withdraw(self, amount):
             time.sleep(0.1)  # Simulate a delay
             self.balance = new_balance
         else:
-            raise Exception("Insufficient balance")
+            raise ValueError("Insufficient balance")
 
 
 account = BankAccount()

thread-safety-locks/bank_rlock.py

@@ -36,16 +36,11 @@ def _update_balance(self, amount):
 
 account = BankAccount()
 
-
-def make_deposit():
-    account.deposit(100)
-
-
 with ThreadPoolExecutor(
     max_workers=3, thread_name_prefix="Worker"
 ) as executor:
     for _ in range(3):
-        executor.submit(make_deposit)
+        executor.submit(account.deposit, 100)
 
 
 print(f"Final balance: {account.balance}")

thread-safety-locks/bank_semaphore.py

@@ -7,13 +7,17 @@
 teller_semaphore = threading.Semaphore(2)
 
 
+def now():
+    return time.strftime("%H:%M:%S")
+
+
 def serve_customer(name):
-    print(f"{int(time.time())}: {name} is waiting for a teller.")
+    print(f"{now()}: {name} is waiting for a teller.")
     with teller_semaphore:
-        print(f"{int(time.time())}: {name} is being served by a teller.")
+        print(f"{now()}: {name} is being served by a teller.")
         # Simulate the time taken for the teller to serve the customer
         time.sleep(random.randint(1, 3))
-        print(f"{int(time.time())}: {name} is done being served.")
+        print(f"{now()}: {name} is done being served.")
 
 
 customers = [
@@ -29,4 +33,4 @@ def serve_customer(name):
         thread = executor.submit(serve_customer, customer_name)
 
 
-print("All customers have been served.")
+print(f"{now()}: All customers have been served.")

thread-safety-locks/bank_thread_safe.py

@@ -16,7 +16,7 @@ def withdraw(self, amount):
                 time.sleep(0.1)  # Simulate a delay
                 self.balance = new_balance
             else:
-                raise Exception("Insufficient balance")
+                raise ValueError("Insufficient balance")
 
     def deposit(self, amount):
         with self.account_lock:
@@ -29,7 +29,6 @@ def deposit(self, amount):
 account = BankAccount(1000)
 
 with ThreadPoolExecutor(max_workers=3) as executor:
-
     executor.submit(account.withdraw, 700)
     executor.submit(account.deposit, 1000)
     executor.submit(account.withdraw, 300)