10+ Senior Staff Engineer Interview Questions and Answers

Design a memory allocator for user space programs like malloc.

• The allocator should manage memory efficiently and avoid fragmentation.

• It should support multiple threads and handle concurrent requests.

• Consider using techniques like buddy allocation or slab allocation.

• Implement features like memory alignment and garbage collection.

• Test the allocator thoroughly to ensure correctness and performance.

OOP in Python is based on four main principles: encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling data and methods that operate on the data within one unit (class). Example: class Dog with attributes and methods.

• Inheritance: Mechanism to create a new class from an existing class, inheriting its properties. Example: class Bulldog inherits from class Dog.

• Polymorphism: Ability to use a common interface for different data types. Example: method ove...read more

I follow the technique of bottom-up estimation for accurate project estimates.

• Break down project into smaller tasks

• Estimate time and resources for each task

• Sum up all estimates for total project estimate

• Consider risks and uncertainties in estimation

• Use historical data for reference

• Adjust estimates based on team expertise and project complexity

DMA in Windows and Linux, different types of IO, and memory APIs in Linux.

• DMA (Direct Memory Access) allows hardware devices to transfer data directly to/from memory without involving the CPU.

• In Windows, DMA is managed by the operating system through the DMA controller. In Linux, DMA is handled by the DMA API.

• Different types of IO include memory-mapped IO, programmed IO, and interrupt-driven IO.

• Memory APIs in Linux include mmap() for memory mapping files into memory and mallo...read more

DOM stands for Document Object Model in JavaScript, it represents the structure of a webpage as a tree of objects.

• DOM is a programming interface for web documents.

• It allows scripts to dynamically access and update the content, structure, and style of a webpage.

• DOM represents the HTML elements as objects that can be manipulated using JavaScript.

Scrum/Agile is a project management framework that emphasizes iterative development, collaboration, and flexibility.

• Scrum is a specific framework within Agile that focuses on delivering value in short iterations called sprints.

• Agile emphasizes adaptability, customer collaboration, and responding to change over following a plan.

• Both Scrum and Agile promote self-organizing teams and continuous improvement.

• Examples of Agile practices include daily stand-up meetings, sprint plann...read more

In-place string manipulation refers to modifying a string without using extra memory space.

• In-place string manipulation involves directly modifying the characters of the original string without creating a new string object.

• Examples include reversing a string in place, converting all characters to uppercase in place, or removing whitespace in place.

• For example, to reverse a string in place: start with two pointers at the beginning and end of the string, swap characters and mov...read more

A key-value store is a data storage system that allows users to store, retrieve, and manage data based on unique keys.

• Use a hash table data structure to store key-value pairs.

• Implement methods for adding, updating, and deleting key-value pairs.

• Include features like data replication, sharding, and data partitioning for scalability.

• Consider data consistency and fault tolerance mechanisms.

• Examples: Redis, MongoDB, Cassandra.

Scalable system design involves creating a system that can handle increased load and growth over time.

• Use microservices architecture to break down the system into smaller, independent services

• Implement load balancing to distribute traffic evenly across servers

• Utilize caching mechanisms to reduce the load on the database

• Design for horizontal scalability by adding more servers to handle increased load

• Consider using cloud services for scalability and flexibility

Implement a coding challenge in PHP

• Use PHP to write a function or class to solve the challenge

• Consider using loops, conditionals, and built-in functions

• Test your code with different inputs to ensure it works correctly

Thermal throttling is a mechanism used to prevent a device from overheating by reducing its performance.

• Thermal throttling is a technique used in electronic devices to prevent overheating.

• When a device reaches a certain temperature threshold, it will reduce its performance to lower the heat generation.

• This can result in slower processing speeds or decreased battery life, but it protects the device from damage.

• Common examples include smartphones, laptops, and gaming consoles t...read more

Design a dictionary that efficiently stores and retrieves key-value pairs with various functionalities.

• Use a hash table for O(1) average time complexity for lookups. Example: {'apple': 'a fruit', 'car': 'a vehicle'}

• Implement collision resolution strategies like chaining or open addressing.

• Support dynamic resizing to handle varying loads efficiently.

• Include methods for adding, removing, and updating entries.

• Consider thread safety if used in a concurrent environment.

To build a side panel, you will need to design, measure, cut, assemble, and attach the panel to the desired structure.

• Design the side panel based on the dimensions and requirements of the structure it will be attached to.

• Measure and mark the material accurately before cutting to ensure a precise fit.

• Cut the material using appropriate tools such as a saw or cutter.

• Assemble the panel by joining the cut pieces together using screws, nails, or adhesive.

• Attach the side panel secur...read more

A rate limiter controls the number of requests a user can make to a service in a given timeframe.

• Token Bucket Algorithm: Allows a burst of requests up to a limit, then enforces a steady rate.

• Leaky Bucket Algorithm: Processes requests at a constant rate, smoothing out bursts.

• Fixed Window Counter: Counts requests in a fixed time window (e.g., 1 minute) and resets after the window ends.

• Sliding Window Log: Keeps a log of timestamps for requests and allows requests based on the ti...read more