Python Coding challenge - Day 1119| What is the output of the following Python Code?

 

Code Explanation:

1️⃣ Importing Threading Module

import threading

Explanation

Imports Python’s threading module.

Used for creating threads and locks.

2️⃣ Creating an RLock

lock = threading.RLock()

Explanation

Creates a Reentrant Lock (RLock).

Special lock that allows same thread to acquire it multiple times.

👉 Unlike normal Lock, this avoids deadlock when re-acquired.

3️⃣ Defining Task Function

def task():

Explanation

Function that will run inside the thread.

4️⃣ First Lock Acquisition

with lock:

Explanation

Thread acquires the lock.

Ensures only one thread enters this block at a time.

5️⃣ Printing First Value

print("A")

Explanation

Prints:

A

6️⃣ Nested Lock Acquisition

with lock:

Explanation ⚠️ IMPORTANT

Same thread tries to acquire the lock again.

Since it's an RLock, this is allowed.

👉 With normal Lock, this would cause deadlock ❌

7️⃣ Printing Second Value

print("B")

Explanation

Prints:

B

8️⃣ Creating Thread

t = threading.Thread(target=task)

Explanation

Creates a thread that will execute task().

9️⃣ Starting Thread

t.start()

Explanation

Thread starts execution.

Runs task().

🔟 Waiting for Completion

t.join()

Explanation

Main thread waits until task() finishes.

📤 Final Output

A

B

Book: Mastering Pandas with Python