
Persistent Systems

20+ Persistent Systems Lead Engineer Interview Questions and Answers
Q1. What is the default connection pooling in Spring Boot, and how can it be customized?
The default connection pooling in Spring Boot is HikariCP, which can be customized through properties in the application.properties file.
HikariCP is the default connection pooling library in Spring Boot, known for its high performance and low overhead.
To customize the connection pooling, you can modify properties like 'spring.datasource.hikari.*' in the application.properties file.
For example, you can set maximum pool size, connection timeout, idle timeout, and other paramete...read more
Q2. What are the best practices for optimizing a Spring Boot application?
Best practices for optimizing a Spring Boot application
Use Spring Boot Actuator to monitor and manage application performance
Implement caching mechanisms like Spring Cache to reduce database calls
Optimize database queries and indexes for better performance
Use asynchronous processing with Spring's @Async annotation for non-blocking operations
Profile and analyze application performance using tools like VisualVM or JProfiler
Q3. What is a heap dump, and how can it be used to identify memory leaks?
A heap dump is a snapshot of the memory usage of a Java application at a specific point in time.
Heap dumps can be generated using tools like jmap or VisualVM.
They provide detailed information about objects in memory, their sizes, and references.
Analyzing a heap dump can help identify memory leaks by pinpointing objects that are consuming excessive memory.
Common signs of memory leaks in a heap dump include a large number of objects of the same type or objects that should have ...read more
Q4. How can you diagonally iterate through and print the elements of a 2D array?program
Diagonally iterate through and print elements of a 2D array of strings.
Use nested loops to iterate through rows and columns of the 2D array.
Calculate the diagonal elements by incrementing row and column indices together.
Print the elements as you iterate through the diagonal of the array.
Q5. Write media query for showing 3 divs in a row for desktop view and in column for mobile view
Media query for 3 divs in row for desktop and column for mobile view
Use min-width and max-width to target desktop and mobile views respectively
Set display property to flex and flex-wrap to wrap for desktop view
Set display property to block for mobile view
Q6. What is the architecture of the Java Virtual Machine (JVM)?
The Java Virtual Machine (JVM) is an abstract computing machine that enables a computer to run Java programs.
JVM is platform-independent and converts Java bytecode into machine code.
It consists of class loader, runtime data areas, execution engine, and native method interface.
JVM memory is divided into method area, heap, stack, and PC register.
Examples of JVM implementations include Oracle HotSpot, OpenJ9, and GraalVM.
Q7. Working concepts of loops , map , list problem statment.
Loops, map, and list are fundamental concepts in programming.
Loops are used to repeat a block of code until a certain condition is met.
Map is a higher-order function that applies a given function to each element of a list and returns a new list.
List is a collection of elements that can be accessed by their index.
Example: for loop, map function, list comprehension.
Q8. Validation on how much exposure to the product
Exposure to the product can be validated through hands-on experience, user feedback, market research, and data analysis.
Hands-on experience with the product through development and testing
User feedback from customers or internal stakeholders
Market research to understand the competitive landscape and user preferences
Data analysis of usage metrics, customer behavior, and product performance
Examples: Conducting user interviews, A/B testing features, analyzing sales data
Q9. How Agile process works
Agile process involves iterative development, collaboration, and flexibility in responding to change.
Agile process breaks down projects into smaller, manageable tasks called sprints.
Teams work in short iterations, typically 2-4 weeks, to deliver working software.
Regular meetings like daily stand-ups, sprint planning, and retrospectives help keep the team on track.
Customer feedback is incorporated throughout the development process to ensure the final product meets their needs...read more
Q10. Customization tools and details
Customization tools and details are essential for tailoring engineering solutions to specific needs.
Customization tools allow for adjusting parameters to meet unique requirements
Details provide a deeper understanding of the system being engineered
Examples include CAD software for designing custom parts and simulation tools for optimizing performance
Q11. create sql queries for different scenarios
Creating SQL queries for different scenarios
Use SELECT statement to retrieve data from a table
Use WHERE clause to filter data based on specific conditions
Use JOIN clause to combine data from multiple tables
Q12. What is TSQL and optimization techniques
TSQL is a Microsoft proprietary extension of SQL used for querying and managing relational databases.
TSQL stands for Transact-SQL and is used in Microsoft SQL Server.
Optimization techniques in TSQL include indexing, query tuning, and avoiding unnecessary joins.
Examples of optimization techniques in TSQL include using appropriate indexes on frequently queried columns and avoiding using functions in WHERE clauses.
Q13. Program to read data from excel
A program to read data from excel.
Use a library like Apache POI or OpenPyXL to read excel files.
Identify the sheet and cell range to read data from.
Parse the data and store it in a suitable data structure.
Handle errors and exceptions that may occur during the process.
Q14. Code on basic trigger
A basic trigger code is used to automatically perform an action when a certain event occurs in a database.
Triggers are written in SQL and can be used to enforce business rules, perform data validation, or maintain data integrity.
Example: CREATE TRIGGER trigger_name BEFORE INSERT ON table_name FOR EACH ROW BEGIN ... END;
Q15. REST and SOAP examples and design principles
REST and SOAP are web service protocols with different design principles
REST (Representational State Transfer) is an architectural style that uses standard HTTP methods like GET, POST, PUT, DELETE for communication
SOAP (Simple Object Access Protocol) is a protocol that uses XML for message exchange and can work over various transport protocols like HTTP, SMTP, etc.
REST is lightweight, scalable, and easy to use, while SOAP is more rigid and has built-in security features
REST i...read more
Q16. Explain the Automation framework
Automation framework is a set of guidelines, standards, and tools used for automating software testing.
It provides a structured approach to automate tests
It includes tools for test case management, test data management, and reporting
It helps in reducing manual effort and increasing test coverage
Examples include Selenium, Appium, and TestNG
Q17. difference between let const and var
let is block scoped, const is constant, var is function scoped
let: block scoped, can be reassigned
const: block scoped, cannot be reassigned, but its properties can be modified
var: function scoped, can be reassigned
Q18. How spring works internally
Spring is a lightweight framework that provides comprehensive infrastructure support for developing Java applications.
Spring works internally by using Inversion of Control (IoC) container to manage Java objects.
It uses Dependency Injection to inject the dependencies of an object at runtime.
Spring also provides Aspect-Oriented Programming (AOP) support for cross-cutting concerns.
It utilizes various modules like Core, Context, AOP, JDBC, ORM, etc., to provide different function...read more
Q19. Program to reverse a string
A program to reverse a string
Iterate through the string from end to start and append each character to a new string
Use built-in functions like reverse() or StringBuilder.reverse() in some programming languages
Convert the string to an array, reverse the array, and then convert it back to a string
Q20. Optimization techniques for react
Optimization techniques for React include code splitting, lazy loading, memoization, and virtualization.
Code splitting: Break down the code into smaller chunks to load only what is necessary for each page.
Lazy loading: Load components only when they are needed, improving initial load time.
Memoization: Cache the results of expensive function calls to avoid redundant calculations.
Virtualization: Render only the visible elements in a list, improving performance for large dataset...read more
Q21. Underlying structure of Databricks
Databricks is built on Apache Spark, a unified analytics engine for big data processing.
Databricks is built on top of Apache Spark, which provides a unified analytics engine for big data processing.
It offers a collaborative platform for data scientists, data engineers, and business analysts to work together.
Databricks provides tools for data ingestion, data processing, machine learning, and visualization.
It supports multiple programming languages like Python, Scala, SQL, and ...read more
Q22. check palindrome in python
Check if a string is a palindrome in Python
Use string slicing to reverse the string and compare with the original string
Remove spaces and convert to lowercase for accurate comparison
Use a for loop to iterate through the string and check if it is a palindrome
Q23. 1Code on Palindrome
A palindrome is a word, phrase, number, or other sequence of characters that reads the same forward and backward.
Check if the string is equal to its reverse to determine if it is a palindrome.
Ignore spaces and punctuation when checking for palindromes.
Examples: 'racecar', 'madam', '12321'
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