| 1 | How would you use jstat to monitor GC activity and heap generation sizes for a running JVM process in real time, without needing a full profiling tool? Java › Garbage Collection | Java | Garbage Collection | Intermediate |
| 2 | How do you use the timeit module to accurately measure a small code snippet's execution time? Python › Debugging & Profiling | Python | Debugging & Profiling | Intermediate |
| 3 | How do you use cProfile to identify which functions are consuming the most time in a larger program? Python › Debugging & Profiling | Python | Debugging & Profiling | Intermediate |
| 4 | How would you use the 'faulthandler' module to diagnose a program that crashes with a segmentation fault, typically from a C extension? Python › Debugging & Profiling | Python | Debugging & Profiling | Advanced |
| 5 | How would you use line_profiler (a third-party tool) to get LINE-BY-LINE timing information within a specific function, more granular than cProfile's function-level data? Python › Debugging & Profiling | Python | Debugging & Profiling | Advanced |
| 6 | How would you use py-spy (a sampling profiler) to profile a running Python process in PRODUCTION without restarting it or adding any code changes? Python › Debugging & Profiling | Python | Debugging & Profiling | Advanced |
| 7 | How do you use the built-in pdb debugger to pause execution at a specific line? Python › Debugging & Profiling | Python | Debugging & Profiling | Beginner |
| 8 | How do you use print statements effectively for debugging, including showing variable names alongside values? Python › Debugging & Profiling | Python | Debugging & Profiling | Beginner |
| 9 | How do you use the traceback module to capture and format a full exception traceback as a string, useful for logging? Python › Debugging & Profiling | Python | Debugging & Profiling | Intermediate |
| 10 | How do assert statements work for debugging, and why should they NOT be relied upon for production input validation? Python › Debugging & Profiling | Python | Debugging & Profiling | Intermediate |
| 11 | How do you use Python's built-in 'warnings' module to surface deprecated or risky code paths during debugging? Python › Debugging & Profiling | Python | Debugging & Profiling | Intermediate |
| 12 | How would you generate and interpret a CPU profile for a Node.js application using the built-in --prof flag? Node.js › Performance Optimization & Profiling | Node.js | Performance Optimization & Profiling | Intermediate |
| 13 | What is load testing, and how would you use a tool like autocannon or k6 to benchmark a Node.js API's throughput and latency? Node.js › Performance Optimization & Profiling | Node.js | Performance Optimization & Profiling | Intermediate |
| 14 | What is the difference between vertical and horizontal performance optimization strategies for a Node.js application, and how do you decide which to pursue first? Node.js › Performance Optimization & Profiling | Node.js | Performance Optimization & Profiling | Intermediate |
| 15 | How do you use memory_profiler (or tracemalloc from the standard library) to identify a memory leak's source in a Python application? Python › Debugging & Profiling | Python | Debugging & Profiling | Advanced |
| 16 | How would you use the 'logging' module's exception logging (logger.exception()) INSIDE an except block to automatically capture the full traceback? Python › Debugging & Profiling | Python | Debugging & Profiling | Advanced |
| 17 | How do you use pdb's post-mortem debugging mode to inspect a program's state exactly at the point where an unhandled exception occurred? Python › Debugging & Profiling | Python | Debugging & Profiling | Advanced |
| 18 | How would you profile memory allocations specifically (not just CPU time) to find which objects are consuming the most memory in a running process? Python › Debugging & Profiling | Python | Debugging & Profiling | Advanced |
| 19 | How do you use conditional breakpoints in pdb to pause execution only when a specific condition is met, avoiding manually stepping through many unrelated iterations? Python › Debugging & Profiling | Python | Debugging & Profiling | Advanced |
| 20 | What is JIT (Just-In-Time) compilation deoptimization in V8, and how can you detect when it's hurting a hot function's performance? Node.js › Performance Optimization & Profiling | Node.js | Performance Optimization & Profiling | Advanced |
| 21 | How would you optimize a Node.js application's JSON serialization performance for API responses with very large or very frequent payloads? Node.js › Performance Optimization & Profiling | Node.js | Performance Optimization & Profiling | Advanced |
| 22 | Why is a bare 'except:' clause (catching everything with no type specified) generally discouraged? Python › Exception Handling | Python | Exception Handling | Beginner |
| 23 | Why should you use the logging module instead of print() for diagnostic output? Python › Logging | Python | Logging | Beginner |
| 24 | What are Python's five standard logging severity levels, from lowest to highest? Python › Logging | Python | Logging | Beginner |
| 25 | How do you format log output to include the timestamp, logger name, level, and message? Python › Logging | Python | Logging | Beginner |
| 26 | What is the difference between __str__ and __repr__? Python › Magic Methods & Operator Overloading | Python | Magic Methods & Operator Overloading | Beginner |
| 27 | How does __repr__ help with debugging when printing a list of custom objects? Python › Magic Methods & Operator Overloading | Python | Magic Methods & Operator Overloading | Beginner |
| 28 | What does it mean that Python has 'automatic' memory management, and what's the trade-off compared to manual memory management in languages like C? Python › Memory Management & Garbage Collection | Python | Memory Management & Garbage Collection | Beginner |
| 29 | What is caching, and why is it commonly used to improve the performance of a Node.js application? Node.js › Caching | Node.js | Caching | Beginner |
| 30 | What is the difference between fs.readFile() and fs.createReadStream() for reading a file in Node.js? Node.js › File System & File Processing | Node.js | File System & File Processing | Beginner |
| 31 | What is a race condition, and how does it differ from a deadlock? Python › Concurrency (asyncio/threading/multiprocessing) | Python | Concurrency (asyncio/threading/multiprocessing) | Intermediate |
| 32 | What is the difference between 'raise' and 'raise ... from ...' for exception chaining? Python › Exception Handling | Python | Exception Handling | Intermediate |
| 33 | How do you access details about the exception currently being handled, like its type, value, and traceback, using sys.exc_info()? Python › Exception Handling | Python | Exception Handling | Intermediate |
| 34 | How does the 'else' clause on a try statement work, and what's its purpose compared to just putting that code at the end of 'try'? Python › Exception Handling | Python | Exception Handling | Intermediate |
| 35 | What is the relationship between Logger, Handler, Formatter, and Filter in the logging module? Python › Logging | Python | Logging | Intermediate |
| 36 | What's the danger of using %-style, f-string, or .format() interpolation directly in a log call's message argument versus lazy % substitution? Python › Logging | Python | Logging | Intermediate |
| 37 | How does Python's generational garbage collector work, and why generations? Python › Memory Management & Garbage Collection | Python | Memory Management & Garbage Collection | Intermediate |
| 38 | What is the sys.getsizeof() function, and what are its limitations for measuring memory usage? Python › Memory Management & Garbage Collection | Python | Memory Management & Garbage Collection | Intermediate |
| 39 | How does the gc module let you inspect and debug memory leaks caused by uncollectable objects? Python › Memory Management & Garbage Collection | Python | Memory Management & Garbage Collection | Intermediate |
| 40 | How do mutable default arguments create a subtle memory and correctness pitfall related to object lifetime? Python › Memory Management & Garbage Collection | Python | Memory Management & Garbage Collection | Intermediate |
| 41 | How does the tracemalloc module help track where memory is being allocated in a running program? Python › Memory Management & Garbage Collection | Python | Memory Management & Garbage Collection | Intermediate |
| 42 | How do you troubleshoot a CORS error reported in browser developer tools, and what does the error message typically indicate? .NET › CORS & Cross-Origin Resource Sharing | .NET | CORS & Cross-Origin Resource Sharing | Intermediate |
| 43 | What is the difference between running async operations sequentially with multiple awaits versus concurrently with Promise.all()? Node.js › Async Patterns | Node.js | Async Patterns | Intermediate |
| 44 | What is job concurrency in a worker process, and how do you configure it safely in BullMQ? Node.js › Background Jobs & Queues | Node.js | Background Jobs & Queues | Intermediate |
| 45 | How would you track and expose the progress of a long-running background job to the client that requested it? Node.js › Background Jobs & Queues | Node.js | Background Jobs & Queues | Intermediate |
| 46 | What HTTP caching headers (Cache-Control, ETag) can a Node.js/Express API use to let clients and CDNs cache responses? Node.js › Caching | Node.js | Caching | Intermediate |
| 47 | How would you implement a Least Recently Used (LRU) cache in Node.js, and why is eviction necessary for an in-memory cache? Node.js › Caching | Node.js | Caching | Intermediate |
| 48 | What is memoization, and how does it differ from a general-purpose external cache like Redis? Node.js › Caching | Node.js | Caching | Intermediate |
| 49 | Why does Node.js provide a cluster module, given that a single Node.js process is single-threaded? Node.js › Clustering & Worker Threads | Node.js | Clustering & Worker Threads | Intermediate |
| 50 | What is the difference between the number of CPU cores and the optimal number of cluster workers for a given Node.js application? Node.js › Clustering & Worker Threads | Node.js | Clustering & Worker Threads | Intermediate |
| 51 | How do you gracefully terminate a worker thread, and what's the difference between worker.terminate() and letting it exit naturally? Node.js › Clustering & Worker Threads | Node.js | Clustering & Worker Threads | Intermediate |
| 52 | What does the node:zlib module provide, and how would you use it to compress an HTTP response? Node.js › Core Node.js Modules | Node.js | Core Node.js Modules | Intermediate |
| 53 | What is a database connection pool, and why does a Node.js application need one rather than opening a new connection per request? Node.js › Databases | Node.js | Databases | Intermediate |
| 54 | What is database normalization, and what specific problems can over-normalization or under-normalization cause? Node.js › Databases | Node.js | Databases | Intermediate |
| 55 | What is the N+1 query problem, and how does it commonly arise in a Node.js application using an ORM? Node.js › Databases | Node.js | Databases | Intermediate |
| 56 | What is a multi-stage Docker build, and why is it commonly used for Node.js applications? Node.js › Docker & Deployment | Node.js | Docker & Deployment | Intermediate |
| 57 | What is the purpose of setting explicit CPU and memory resource requests and limits for a Node.js container in Kubernetes? Node.js › Docker & Deployment | Node.js | Docker & Deployment | Intermediate |
| 58 | What does 'non-blocking I/O' mean, and how does a Node.js function like fs.readFile() achieve it compared to fs.readFileSync()? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Intermediate |
| 59 | How does setImmediate() differ from process.nextTick() in terms of timing and typical use cases? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Intermediate |
| 60 | How does the event loop handle a large synchronous loop (like processing a huge array with a for loop), and what problem does this cause? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Intermediate |
| 61 | How would you measure how 'busy' the event loop is in a running Node.js process using a simple technique? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Intermediate |
| 62 | What is the difference between fs.appendFile() and opening a file with the 'a' flag and writing to it manually? Node.js › File System & File Processing | Node.js | File System & File Processing | Intermediate |
| 63 | How would you copy a large file efficiently in Node.js, and what's the difference between fs.copyFile() and manually piping streams? Node.js › File System & File Processing | Node.js | File System & File Processing | Intermediate |
| 64 | What is the difference between npm, Yarn, and pnpm as Node.js package managers, and what specific advantage does pnpm offer regarding disk space? Node.js › Git & Project Management | Node.js | Git & Project Management | Intermediate |
| 65 | What is the difference between HTTP/1.1 and HTTP/2, and how does Node.js support HTTP/2 via the node:http2 module? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Intermediate |
| 66 | What is HTTP keep-alive, and how does it improve performance for a Node.js server handling many requests from the same client? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Intermediate |
| 67 | What is the purpose of the Content-Length and Transfer-Encoding: chunked headers, and why can't a response use both simultaneously? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Intermediate |
| 68 | What Redis data structures beyond simple string values are useful for a Node.js application, and what are they typically used for? Node.js › Caching with Redis | Node.js | Caching with Redis | Intermediate |
| 69 | How would you read a large file efficiently using a stream rather than loading it entirely into memory with fs.readFile()? Node.js › File System (fs) Module | Node.js | File System (fs) Module | Intermediate |
| 70 | What is over-fetching and under-fetching in REST APIs, and how does GraphQL specifically address both? Node.js › GraphQL with Node.js | Node.js | GraphQL with Node.js | Intermediate |
| 71 | What is HTTP keep-alive, and how does Node's http.Agent manage connection reuse for outgoing requests? Node.js › HTTP & HTTPS Modules | Node.js | HTTP & HTTPS Modules | Intermediate |
| 72 | What is an APM (Application Performance Monitoring) tool, and what capabilities does it typically add beyond basic logging? Node.js › Logging & Monitoring | Node.js | Logging & Monitoring | Intermediate |
| 73 | What is the V8 JavaScript engine, and what role does it play within the Node.js runtime? Node.js › Node.js Fundamentals & Runtime Architecture | Node.js | Node.js Fundamentals & Runtime Architecture | Intermediate |
| 74 | How do you profile a MAUI app to find performance bottlenecks? .NET MAUI › Performance & Optimization | .NET MAUI | Performance & Optimization | Advanced |
| 75 | How do you profile a MAUI app to find performance bottlenecks? .NET MAUI › Performance & Optimization | .NET MAUI | Performance & Optimization | Advanced |
| 76 | How would you profile whether a generator expression is actually providing a measurable memory or performance benefit over a list comprehension in a specific use case? Python › Comprehensions & Generators | Python | Comprehensions & Generators | Advanced |
| 77 | How would you choose between a list, a set, a dict, and a specialized structure like heapq for efficiently finding the K smallest/largest elements in a large dataset? Python › Data Types & Structures | Python | Data Types & Structures | Advanced |
| 78 | How do you implement a descriptor-based ORM-style field that lazily loads related data only when actually accessed? Python › Descriptors & Properties | Python | Descriptors & Properties | Advanced |
| 79 | How does exception performance (raising/catching) compare to normal control flow, and why does Python's EAFP style still encourage using exceptions for routine control flow, unlike some other languages? Python › Exception Handling | Python | Exception Handling | Advanced |
| 80 | How do you correctly handle character encoding when reading text files that might not be UTF-8, and what error occurs if you guess wrong? Python › File I/O & Context Managers | Python | File I/O & Context Managers | Advanced |
| 81 | Why is using a mutable default argument (like an empty list) a classic Python bug, and how do you avoid it? Python › Functions & Scope | Python | Functions & Scope | Advanced |
| 82 | How do you clear or inspect the cache of an lru_cache-decorated function? Python › functools & Functional Programming Tools | Python | functools & Functional Programming Tools | Advanced |
| 83 | How does itertools.groupby depend on input order, and what's a common mistake when using it? Python › Iterators & the Iterator Protocol | Python | Iterators & the Iterator Protocol | Advanced |
| 84 | How does logger.exception() differ from logger.error(), and when should you use it? Python › Logging | Python | Logging | Advanced |
| 85 | How would you write a custom logging.Filter to redact sensitive data like passwords from log messages? Python › Logging | Python | Logging | Advanced |
| 86 | How does object interning (like small integer caching and string interning) affect memory and identity comparisons? Python › Memory Management & Garbage Collection | Python | Memory Management & Garbage Collection | Advanced |
| 87 | What is memory fragmentation in the context of Python's object allocator, and how does pymalloc address it for small objects? Python › Memory Management & Garbage Collection | Python | Memory Management & Garbage Collection | Advanced |
| 88 | How do circular references between objects with __del__ methods behave differently in Python 3.4+ compared to earlier versions? Python › Memory Management & Garbage Collection | Python | Memory Management & Garbage Collection | Advanced |
| 89 | How does Python locate modules during import, and what is sys.path's role? Python › Modules & Packaging | Python | Modules & Packaging | Advanced |
| 90 | Why does Python sometimes raise 'TypeError: Cannot create a consistent method resolution order'? Python › Multiple Inheritance & MRO | Python | Multiple Inheritance & MRO | Advanced |
| 91 | What is the libuv library, and what specific role does it play inside Node.js? Node.js › Advanced Node.js | Node.js | Advanced Node.js | Advanced |
| 92 | How do you use the --inspect flag and Chrome DevTools to profile a running Node.js application in production? Node.js › Advanced Node.js | Node.js | Advanced Node.js | Advanced |
| 93 | What is V8's hidden class mechanism, and why does it matter for writing performant Node.js code? Node.js › Advanced Node.js | Node.js | Advanced Node.js | Advanced |
| 94 | What is backpressure in Node.js streams, and how do you handle it correctly when piping data? Node.js › Advanced Node.js | Node.js | Advanced Node.js | Advanced |
| 95 | What is monkey-patching in the context of Node.js APM (Application Performance Monitoring) tools, and what are its risks? Node.js › Advanced Node.js | Node.js | Advanced Node.js | Advanced |
| 96 | How would you implement a concurrency-limited task queue in Node.js to process many async tasks without overwhelming a downstream resource? Node.js › Async Patterns | Node.js | Async Patterns | Advanced |
| 97 | How do you implement job prioritization in a Node.js queue system, and when is it necessary? Node.js › Background Jobs & Queues | Node.js | Background Jobs & Queues | Advanced |
| 98 | What is cache stampede (thundering herd), and how do you prevent it in a high-traffic Node.js service? Node.js › Caching | Node.js | Caching | Advanced |
| 99 | What is the 'stale-while-revalidate' caching strategy, and how would you implement it for an API response? Node.js › Caching | Node.js | Caching | Advanced |
| 100 | What is multi-tier caching (combining an in-memory L1 cache with a distributed L2 cache), and what problem does it solve? Node.js › Caching | Node.js | Caching | Advanced |
| 101 | How would you implement a write-behind (write-back) caching strategy, and what durability risk does it introduce? Node.js › Caching | Node.js | Caching | Advanced |
| 102 | What is auto-scaling, and what metrics commonly trigger scaling decisions for a Node.js service running in the cloud? Node.js › Cloud & DevOps | Node.js | Cloud & DevOps | Advanced |
| 103 | How do you use SharedArrayBuffer to share memory directly between Node.js worker threads, and what are the safety considerations? Node.js › Clustering & Worker Threads | Node.js | Clustering & Worker Threads | Advanced |
| 104 | What is a worker thread pool, and why would you build one rather than creating a new Worker for every task? Node.js › Clustering & Worker Threads | Node.js | Clustering & Worker Threads | Advanced |
| 105 | What does the node:perf_hooks module provide, and how would you use it to measure precise execution time of a code block? Node.js › Core Node.js Modules | Node.js | Core Node.js Modules | Advanced |
| 106 | What is database indexing, and how does an index improve query performance in a Node.js application's database layer? Node.js › Databases | Node.js | Databases | Advanced |
| 107 | What is database replication, and how does a Node.js application typically route reads to replicas while sending writes to a primary? Node.js › Databases | Node.js | Databases | Advanced |
| 108 | What is database sharding, and what problem does it solve that replication alone doesn't address? Node.js › Databases | Node.js | Databases | Advanced |
| 109 | What is a database connection leak in a Node.js application, and how does it typically happen when using a connection pool? Node.js › Databases | Node.js | Databases | Advanced |
| 110 | How would you optimize Docker layer caching in a Node.js Dockerfile to speed up repeated builds during development? Node.js › Docker & Deployment | Node.js | Docker & Deployment | Advanced |
| 111 | What is 'event loop lag' (or 'event loop delay'), and how would you monitor it in a production Node.js application? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Advanced |
| 112 | What is the poll phase of the event loop, and under what specific conditions does it block waiting versus move on immediately? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Advanced |
| 113 | How would you implement a request-logging middleware in Express that captures method, path, status code, and response time for every request? Node.js › Express & Middleware | Node.js | Express & Middleware | Advanced |
| 114 | How would you implement conditional middleware in Express that only applies to certain requests based on a runtime condition? Node.js › Express & Middleware | Node.js | Express & Middleware | Advanced |
| 115 | How would you implement a global request timeout middleware in Express to prevent a slow request from hanging indefinitely? Node.js › Express & Middleware | Node.js | Express & Middleware | Advanced |
| 116 | How would you implement a directory-size calculator in Node.js that recursively sums the size of all files within a directory tree? Node.js › File System & File Processing | Node.js | File System & File Processing | Advanced |
| 117 | What is the N+1 query problem in GraphQL specifically, and how does DataLoader solve it? Node.js › GraphQL | Node.js | GraphQL | Advanced |
| 118 | How would you implement query complexity analysis or depth limiting in a GraphQL API to prevent a maliciously deep or expensive query from overwhelming the server? Node.js › GraphQL | Node.js | GraphQL | Advanced |
| 119 | How would you implement HTTP/2 server push in Node.js, and why has server push become less commonly recommended over time? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Advanced |
| 120 | How would you implement HTTP/2 or HTTP/1.1 connection pooling on the client side in Node.js when making many outgoing requests to the same downstream API? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Advanced |
| 121 | How would you implement HTTP response streaming in Node.js to begin sending data to a client before the entire response is ready, such as for a large report? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Advanced |
| 122 | What is the N+1 query problem in the context of an ORM like Mongoose or Sequelize, and how do you avoid it? Node.js › Databases & ORMs (MongoDB/Mongoose, SQL/Sequelize) | Node.js | Databases & ORMs (MongoDB/Mongoose, SQL/Sequelize) | Advanced |
| 123 | How would you use the 'clinic.js' toolset (clinic doctor, clinic flame) to diagnose a Node.js performance problem? Node.js › Debugging & Diagnostics | Node.js | Debugging & Diagnostics | Advanced |
| 124 | What does PM2's built-in monitoring dashboard (pm2 monit, or PM2 Plus) show, and what metrics are most useful for production operations? Node.js › Deployment & Process Managers (PM2) | Node.js | Deployment & Process Managers (PM2) | Advanced |
| 125 | What are Node.js file descriptor limits, and how might a Node.js application unintentionally exhaust them? Node.js › File System (fs) Module | Node.js | File System (fs) Module | Advanced |
| 126 | What is the N+1 query problem specific to GraphQL, and how does DataLoader solve it? Node.js › GraphQL with Node.js | Node.js | GraphQL with Node.js | Advanced |
| 127 | How would you implement HTTP/2 server push or basic HTTP/2 support in Node.js using the node:http2 module? Node.js › HTTP & HTTPS Modules | Node.js | HTTP & HTTPS Modules | Advanced |