100+ Senior Software Engineer 2 Interview Questions and Answers

Use compensating transactions and distributed tracing for managing transaction and logging in case of service B failure.

• Implement compensating transactions to rollback changes made by service B in case of failure.

• Use distributed tracing to track the flow of requests and identify where the failure occurred.

• Implement retry mechanisms to handle transient failures in service B.

• Use circuit breakers to prevent cascading failures in the system.

• Implement centralized logging to captur...read more

System diagram for e-commerce order placement and history retrieval

• Frontend: Customer interface for browsing products, adding to cart, and placing orders

• Backend: Order processing system to handle order placement, payment processing, and order fulfillment

• Database: Store customer information, order details, and order history for retrieval

• APIs: Communication between frontend, backend, and database for seamless order processing

• Analytics: Track order history and customer behavior ...read more

HashMap internally uses an array of linked lists to store key-value pairs. To store duplicate keys, we can use a custom implementation of HashMap.

• HashMap internally uses an array of linked lists to handle collisions.

• To store duplicate keys, we can create a custom HashMap implementation that allows multiple values for the same key.

• One approach is to use a HashMap with values as lists, where each key can have multiple values associated with it.

The @Service annotation is used in Spring framework to indicate that a class is a service component.

• Used to mark a class as a service component in Spring framework

• Helps in auto-detection and auto-configuration of Spring beans

• Facilitates dependency injection and inversion of control

Program to convert integer to Excel column name, find first non-repeating character in a string, and create a map of last names with count of names.

• For converting integer to Excel column name, you can use a recursive function to map the remainder of the division by 26 to the corresponding letter.

• To find the first non-repeating character in a string, you can iterate through the string and use a HashMap to store the count of each character.

• For creating a map of last names with ...read more

Java 8 features like lambda expressions and functional interfaces make coding with streams easier and more efficient.

• Lambda expressions allow for concise and readable code when working with streams.

• Functional interfaces like Predicate, Function, and Consumer can be used with streams to perform operations on elements.

• Stream API provides methods like map, filter, and reduce for processing collections of data in a declarative way.

• Parallel streams enable concurrent processing of ...read more

Optional in Java 8 is used to represent a value that may or may not be present, reducing the chances of NullPointerException.

• Optional is used to avoid NullPointerException by explicitly stating whether a value is present or not.

• Commonly used methods with Optional include isPresent(), get(), orElse(), orElseGet(), and map().

• Example: Optional<String> optionalString = Optional.ofNullable("Hello");

Design a parking lot system with features like ticketing, payment, and space availability tracking.

• Create a class for ParkingLot with attributes like total number of spaces, available spaces, and ticketing system.

• Implement methods for issuing tickets, calculating parking fees, and updating space availability.

• Consider implementing a payment system for customers to pay for parking.

• Include features like tracking available spaces, handling multiple levels or sections in the parki...read more

Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Singleton pattern can be implemented by making the constructor private and providing a static method to access the instance.

• The pattern can be broken by using reflection to access the private constructor and create multiple instances.

• Another way to break the Singleton pattern is by using multiple class loaders in Java.

• Thread synchronization issues can also lead to breaking the ...read more

Inter-service communication in microservices involves using protocols like HTTP, gRPC, or messaging queues.

• Microservices communicate with each other through APIs using protocols like HTTP or gRPC.

• Message queues like RabbitMQ or Kafka can be used for asynchronous communication between services.

• Service discovery tools like Consul or Eureka help services locate each other dynamically.

• API gateways can be used to manage and secure communication between services.

• Event-driven archit...read more

Types of dependency injection include constructor injection, setter injection, and interface injection.

• Constructor injection: Dependencies are provided through a class's constructor.

• Setter injection: Dependencies are provided through setter methods.

• Interface injection: Dependencies are provided through an interface method.

Multiple inheritance is a feature in object-oriented programming where a class can inherit attributes and methods from more than one parent class.

• Allows a class to inherit from multiple parent classes, combining their attributes and methods

• Can lead to the diamond problem where ambiguity arises if two parent classes have a method with the same name

• Achieved in languages like C++ using virtual inheritance or interfaces in languages like Java

RestTemplate is a synchronous client for making HTTP requests, while Feign Client is a declarative HTTP client that simplifies making API calls.

• RestTemplate is part of the Spring framework and requires manual configuration for each request.

• Feign Client is a declarative client that uses annotations to define API endpoints and parameters.

• RestTemplate is synchronous, blocking the calling thread until the response is received.

• Feign Client is asynchronous by default, allowing for ...read more

Transaction management in Spring Boot ensures data integrity by managing database transactions.

• Spring Boot uses @Transactional annotation to manage transactions

• It ensures that all operations within a transaction are completed successfully or rolled back if an error occurs

• Transactions can be managed programmatically using TransactionTemplate

• Supports different transaction isolation levels like READ_COMMITTED, REPEATABLE_READ, etc.

Implement LRU cache with expiration, priority, and recentness based eviction policy.

• Use a doubly linked list to keep track of the order of elements based on recentness.

• Use a hashmap to store key-value pairs for quick access.

• Implement a priority queue to handle eviction based on priority.

• Set expiration time for each element and remove expired elements during access or eviction.

Design a system to handle 10 lacs transactions per second.

• Use distributed systems and load balancing to handle the high volume of transactions.

• Implement caching mechanisms to reduce database load.

• Use high-performance hardware and optimize code for speed.

• Consider using a NoSQL database for faster read/write operations.

• Implement fault-tolerant mechanisms to ensure system reliability.

• Use asynchronous processing to handle requests quickly.

• Consider using a message queue to handle ...read more

Pseudo code to sort a random list of numbers in ascending order

• Loop through the list and compare adjacent elements

• If the left element is greater than the right element, swap them

• Repeat until no swaps are needed

Dynamic programming solution to find minimum cost of painting houses with no adjacent houses of same color

• Create a 2D dp array to store the minimum cost of painting each house with each color

• Iterate through each house and each color option, updating the dp array with the minimum cost

• Return the minimum cost of painting the last house

Create a Shell script to add 100 users on 5 different servers.

• Use a loop to create 100 users on each server.

• Utilize the 'useradd' command to add users.

• Ensure unique usernames for each user on each server.

• Consider using SSH for remote server access.

• Test the script on a single server before running on all servers.

Create a custom hashmap with OOPs concepts

• Create a class for the hashmap with private variables for key and value

• Implement methods for adding, removing and retrieving elements

• Use inheritance to create a separate class for each type of data to be stored

• Use encapsulation to protect the data and ensure proper access

• Use polymorphism to allow for different types of data to be stored in the same hashmap

Program to find pair of elements whose sum matches to k

• Use a hash set to store elements as you iterate through the array

• For each element, check if k minus the element is already in the set

• If found, return the pair of elements

• Time complexity: O(n)

Program to swap two numbers without using temp variables

• Use arithmetic operations to swap the values

• Add the two numbers and store the result in the first variable

• Subtract the second variable from the result and store it in the second variable

Python scripting is a way to automate tasks using Python programming language.

• Python scripting allows for automating repetitive tasks by writing scripts in Python.

• It is commonly used for tasks like data processing, web scraping, and automation.

• Python scripts can be run from the command line or integrated into larger applications.

• Python's extensive standard library makes it easy to work with files, networks, and more.

AngularJS is the first version of Angular, while Angular refers to versions 2 and above.

• AngularJS is based on JavaScript, while Angular is based on TypeScript.

• AngularJS uses controllers and $scope for data binding, while Angular uses components and directives.

• AngularJS has two-way data binding, while Angular has one-way data binding by default.

Fault tolerance in microservices ensures system reliability by handling failures gracefully.

• Microservices architecture breaks down applications into smaller, independent services.

• Each microservice is designed to be resilient to failures and can continue to operate even if one service fails.

• Fault tolerance is achieved through redundancy, monitoring, and graceful degradation.

• Examples of fault tolerance mechanisms include circuit breakers, retries, and fallback mechanisms.

Steps to write an immutable class

• Make the class final so it cannot be extended

• Make all fields private and final

• Do not provide setter methods for the fields

• Ensure that any mutable objects within the class are also immutable

• If a mutable object must be returned, make a deep copy before returning it

I have used various types of API methods including GET, POST, PUT, and DELETE.

• GET method is used to retrieve data from a server. For example, I have used GET method to fetch user information from a user API endpoint.

• POST method is used to send data to a server to create a new resource. I have used POST method to create new records in a database through API calls.

• PUT method is used to update existing data on a server. For instance, I have used PUT method to update user informa...read more

Divisions in a COBOL program include Identification, Environment, Data, Procedure, and File Control.

• Identification Division: Contains program name, author, and other identifying information.

• Environment Division: Specifies the hardware and software environment in which the program will run.

• Data Division: Defines the data structures used in the program.

• Procedure Division: Contains the actual logic and processing instructions.

• File Control Division: Specifies the files used by th...read more

Slicing in Python doesn't give index out of bounds error because it automatically handles out of range indices.

• Python slicing allows accessing elements in a sequence using a start and end index.

• If the start or end index is out of range, Python automatically adjusts it to the nearest valid index.

• This behavior prevents index out of bounds errors and makes slicing more convenient.

• For example, slicing a list with an out of range index will return an empty list instead of throwing...read more

Implementing resiliency in microservice architecture involves using techniques like circuit breakers, retries, timeouts, and load balancing.

• Use circuit breakers to prevent cascading failures by stopping requests to a service that is not responding.

• Implement retries with exponential backoff to handle transient failures and give the service time to recover.

• Set timeouts for requests to avoid blocking resources and waiting indefinitely.

• Use load balancing to distribute traffic eve...read more

I designed the HLD for our current project implementation.

• Identified the main components and their interactions

• Created a high-level architecture diagram

• Considered scalability, maintainability, and performance

• Collaborated with team members to ensure alignment with requirements

Lifecycle methods of authentication methods are functions that are executed at different stages of the authentication process.

• Lifecycle methods are used to perform actions before, during, and after authentication.

• Examples of lifecycle methods include initialization, authentication, authorization, and cleanup.

• These methods can be used to validate user credentials, generate access tokens, enforce security policies, and log authentication events.

Traits in PHP are a mechanism for code reuse in single inheritance languages.

• Traits are a way to group functionality in a fine-grained and consistent way.

• They allow developers to reuse sets of methods freely in several independent classes.

• To use a trait in PHP, you use the 'use' keyword followed by the trait name.

• Traits can be composed into a class using multiple 'use' statements.

• Traits can also have abstract methods that must be implemented by the class using the trait.

Var and dynamic are type inference keywords in C#. Static constructors are used to initialize static fields. Private constructors restrict object creation. Microservices are a software architecture pattern.

• Var and dynamic are used for type inference in C#

• Static constructors are used to initialize static fields

• Private constructors restrict object creation

• Microservices are a software architecture pattern for building complex applications as a suite of small, independent service...read more

Standard processes and practices are established methods and guidelines for software development.

• Standard processes and practices ensure consistency and quality in software development.

• Examples include Agile, Waterfall, and DevOps methodologies.

• They often involve documentation, testing, and code reviews.

• They may also include tools and technologies such as version control and continuous integration.

• Adherence to standard processes and practices can improve efficiency and reduce...read more

The coin change problem - given a set of coins and a target amount, find the minimum number of coins needed to make the change.

• Create an array to store the minimum number of coins needed for each amount from 0 to target

• Iterate through each coin and update the array for each amount that can be made using that coin

• Return the value at the target index of the array

Test cases for a dummy website include checking functionality, usability, security, and performance.

• Verify that all links and buttons are working correctly

• Test user registration and login functionality

• Check for proper error messages when entering invalid data

• Test the website's responsiveness on different devices

• Ensure that user data is stored securely

• Perform load testing to check website performance under heavy traffic

To connect to S3 in AWS, you can use the AWS SDK package.

• Use the AWS SDK for your preferred programming language

• Import the necessary libraries and configure your AWS credentials

• Create an S3 client object and specify the AWS region

• Use the client object to interact with S3, such as uploading, downloading, or listing objects

Designing a RESTful API for CRUD operations on a Product table

• Use HTTP methods like GET, POST, PUT, DELETE for CRUD operations

• Create endpoints like /products for listing all products, /products/{id} for specific product, etc.

• Use JSON format for request and response bodies

• Implement authentication and authorization mechanisms for secure access

When a domain is entered in a browser, the browser goes through a series of steps to retrieve and display the website.

• Browser checks cache for DNS records to find IP address of the domain

• If not found, browser sends a DNS query to resolve the domain name to an IP address

• Browser establishes a TCP connection with the server hosting the website

• Browser sends an HTTP request to the server for the specific webpage

• Server processes the request and sends back an HTTP response with the ...read more

OOPS is a programming paradigm based on objects, Inheritance is a mechanism in OOPS, SQL basics include querying databases.

• OOPS stands for Object-Oriented Programming, where data and behavior are encapsulated within objects.

• Inheritance is a mechanism in OOPS where a class inherits properties and behaviors from another class.

• SQL basics include querying databases using SELECT, INSERT, UPDATE, DELETE statements.

• Example: In OOPS, a Car class can inherit properties and behaviors f...read more

LVM stands for Logical Volume Manager. It is a tool used to manage disk space by creating logical volumes from physical volumes.

• LVM allows for dynamic resizing of logical volumes without the need to unmount the filesystem.

• It can create multiple logical volumes from a single physical volume.

• LVM provides features like snapshots and mirroring for data protection.

• The number of partitions that can be created using LVM depends on the size of the physical volumes and the filesystem ...read more

Merge combines changes from different branches, while rebase moves the current branch to the tip of another branch.

• Merge creates a new commit with the combined changes of two branches.

• Rebase moves the current branch to the tip of another branch, replaying the commits on top of it.

• Merge preserves the commit history of both branches, while rebase creates a linear history.

• Merge is non-destructive and is preferred for preserving history, while rebase is useful for keeping a clean...read more

Implement a Smoke Collector problem

• Create a class SmokeCollector with methods to collect smoke data

• Implement a method to start collecting smoke data

• Design a method to analyze and store the collected smoke data

Auto scaling of EC2 instances involves setting up policies to automatically adjust the number of instances based on demand.

• Set up CloudWatch alarms to monitor metrics like CPU utilization or network traffic

• Create an Auto Scaling Group with desired minimum and maximum number of instances

• Define scaling policies to add or remove instances based on the alarms triggered

• Test the auto scaling by simulating load on the instances

To write a procedure in PL/1, use the PROC statement followed by the procedure name and the necessary code.

• Begin with the PROC statement followed by the procedure name

• Add the necessary code within the procedure

• End the procedure with the END statement

• Example: PROC MYPROC; /* code here */ END MYPROC;

Implement security measures like authentication, authorization, encryption, and input validation to protect web apps and APIs.

• Use HTTPS to encrypt data transmitted between clients and servers

• Implement authentication mechanisms like OAuth, JWT, or API keys

• Enforce proper authorization checks to control access to resources

• Sanitize and validate input data to prevent injection attacks

• Regularly update dependencies and libraries to patch security vulnerabilities