Python (ME-506) - Important Questions

Explain the differences between multithreading and multiprocessing in Python. Discuss the Global Interpreter Lock (GIL) and its implications for CPU-bound and I/O-bound tasks. Write a complete Python program using the threading module that demonstrates concurrent I/O-bound tasks and then modify the program to use multiprocessing for a CPU-bound computation. Explain why one approach is preferable over the other for each case.

Write a TCP client-server pair in Python using the socket module to transfer a binary file from client to server. The server should accept connections, receive the file, save it to disk, and send an acknowledgment. Include appropriate exception handling, graceful shutdown, and comments explaining key steps.

Demonstrate how to connect to an SQLite (or MySQL) database from Python. Write code to create a table for student records ($id$, $name$, $marks$), insert multiple records using parameterized queries, update a record, delete a record, and fetch records filtered by a condition. Explain the importance of transactions and how to handle database exceptions.

Explain Python exception hierarchy and the use of try, except, else, and finally blocks. Define a custom exception class and implement a context manager (using either the class-based protocol or the @contextmanager decorator) that manages a resource safely. Provide code examples.

Describe text and binary file modes in Python. Explain how to perform random access using file.seek() and how to read and write fixed-size records. Demonstrate an efficient method to process a very large text file (several gigabytes) line by line without loading it into memory.

Write regular expressions in Python to validate: (a) an email address of the form local@domain (simple validation), and (b) Indian mobile numbers (10 digits, starting with 6-9). Explain the use of raw strings (r"...") and capturing groups. Provide Python code that uses the re module to find and extract the username and domain from an email.

Design a GUI application in Python using Tkinter that allows the user to enter student details ($name$, $roll\,no.$, $marks$) and save them into an SQLite database. The GUI should include form validation (e.g., numeric checks for marks), buttons to Add, Update, Delete, and View records, and a list or table widget to display stored records. Provide the complete code and explain how event handling and database interactions are wired together.

Explain how to perform web scraping in Python using the requests and BeautifulSoup libraries. Write a program that extracts article titles and links from multiple pages of a blog (handle pagination). Discuss how to respect robots.txt, implement polite scraping (rate limiting), and handle common issues like dynamic content and request failures.

Write unit tests for a Python function that interacts with an external API to fetch JSON data. Use the unittest framework (or pytest) and demonstrate how to use mocking to replace network calls so tests run offline and deterministically. Provide example test cases and explain the role of setup and teardown methods.

Explain synchronization primitives provided by the threading module: Lock, RLock, Semaphore, Event, and Condition. Implement a producer-consumer problem using a bounded buffer in Python with appropriate synchronization to avoid race conditions and deadlocks. Provide the code and explain how the chosen primitives ensure correctness.