▸case-01 Our production API service crashes once a week under heavy traffic, but developers usually try tweaking timeout parameters directly in production to see if it stops. What initial approach should be taken before attempting any fix? | fail→pass | 10,554 | 9,043 | -14% | 1 | 1 | 0% | 1,744 | 1,579 | -9% | 0 | 0 | — |
▸case-02 A microservice API response latency jumped from 50ms to 800ms over the past 50 commits. Developers are planning to manually audit code diffs commit by commit. What search technique should be used to isolate the responsible commit efficiently? | pass→pass | 8,235 | 7,585 | -8% | 1 | 1 | 0% | 1,524 | 1,416 | -7% | 0 | 0 | — |
▸case-03 A Java application experiences worker process crashes from OutOfMemoryError after 12 hours. The team wants to increase JVM heap memory from 4GB to 16GB immediately as a quick patch. How should the team systematically validate the root cause? | fail→pass | 15,935 | 15,908 | -0% | 1 | 1 | 0% | 2,647 | 2,633 | -1% | 0 | 0 | — |
▸case-20 We need to design a new REST API endpoint for user registration that accepts email and password, hashes the password with bcrypt, and stores the user in PostgreSQL. Please draft the API implementation. | pass→pass | 11,083 | 8,847 | -20% | 1 | 1 | 0% | 2,432 | 2,169 | -11% | 0 | 0 | — |
▸case-04 A distributed workflow silently drops messages in 1 out of 10,000 transactions. The team considers turning on global TRACE-level logging across all 50 production microservices. What targeted strategy isolates the failing component with lower overhead? | pass→pass | 14,702 | 12,660 | -14% | 1 | 1 | 0% | 2,308 | 2,082 | -10% | 0 | 0 | — |
▸case-05 An incident commander needs a comprehensive step-by-step incident playbook and verification checklist for systematically resolving a database connection pool starvation issue. Where within the project structure should they look? | fail→pass | 7,683 | 2,132 | -72% | 1 | 1 | 0% | 1,406 | 486 | -65% | 0 | 0 | — |
▸case-06 A Python web application throws `AttributeError: 'NoneType' object has no attribute 'get'` deep in a nested service call. A developer proposes wrapping the entire block in a generic `except Exception: pass`. What systematic action should be taken instead? | pass→fail | 13,075 | 8,393 | -36% | 1 | 1 | 0% | 2,218 | 1,639 | -26% | 0 | 0 | — |
▸case-07 In an HTTP microservice architecture using OpenTelemetry, downstream requests fail with 500 errors, but backend logs cannot be linked to frontend HTTP requests. Developers are manually matching timestamps across servers. What mechanism resolves this visibility gap? | pass→pass | 9,812 | 8,056 | -18% | 1 | 1 | 0% | 1,767 | 1,613 | -9% | 0 | 0 | — |
▸case-08 A 5000-line YAML configuration file causes a parser error on startup without indicating a line number. Developers plan to inspect line by line. What strategy rapidly locates the syntactically invalid section? | pass→fail | 10,477 | 9,167 | -13% | 1 | 1 | 0% | 1,936 | 1,712 | -12% | 0 | 0 | — |
▸case-09 A compiled Linux C binary hangs indefinitely during startup without emitting any stdout or stderr messages. A developer wants to rewrite the initialization code in Python. What runtime diagnostic tool should be attached first? | pass→pass | 7,712 | 6,463 | -16% | 1 | 1 | 0% | 1,399 | 1,262 | -10% | 0 | 0 | — |
▸case-10 A Node.js backend worker consumes 100% CPU upon receiving specific payload types. The team plans to double the cloud server vCPU count. What diagnostic step identifies the exact function causing compute saturation? | pass→pass | 9,811 | 8,365 | -15% | 1 | 1 | 0% | 1,802 | 1,692 | -6% | 0 | 0 | — |
▸case-11 A C++ daemon terminates abruptly in production leaving a core dump file. Developers want to add print statements and redeploy to catch the next crash. What tool should analyze the core file immediately? | pass→pass | 6,596 | 5,219 | -21% | 1 | 1 | 0% | 1,171 | 1,140 | -3% | 0 | 0 | — |
▸case-12 An issue occurs only when high network latency and database contention happen simultaneously. Developers want to refactor the database ORM completely. What approach systematically verifies if network latency is the primary trigger? | pass→pass | 14,083 | 10,604 | -25% | 1 | 1 | 0% | 2,531 | 2,127 | -16% | 0 | 0 | — |
▸case-13 After applying a proposed bug fix for a race condition in an asynchronous queue, a developer wants to merge the PR immediately because manual testing succeeded once. What verification process must be completed before closing the issue? | pass→pass | 8,839 | 9,355 | +6% | 1 | 1 | 0% | 1,593 | 1,934 | +21% | 0 | 0 | — |
▸case-14 A TLS handshake failure occurs intermittently between two internal services without detailed application log output. The developer plans to upgrade the operating system. What network analysis tool captures the raw TCP exchange? | pass→pass | 4,756 | 5,294 | +11% | 1 | 1 | 0% | 909 | 1,138 | +25% | 0 | 0 | — |
▸case-15 A Java application experiences a slow memory leak in production. Developers plan to restart the application automatically every 4 hours via cron. What diagnostic artifact should be captured before restarting? | pass→pass | 6,252 | 8,236 | +32% | 1 | 1 | 0% | 1,117 | 1,531 | +37% | 0 | 0 | — |
▸case-16 An application exhibits high disk I/O latency on Linux, but standard user-space logs report normal execution times. Developers are planning to replace all SSD storage hardware. What kernel-level tracing framework pinpoints latency breakdown? | pass→pass | 11,478 | 11,976 | +4% | 1 | 1 | 0% | 2,139 | 2,391 | +12% | 0 | 0 | — |
▸case-17 A major outage caused by a deadlocked database transaction was resolved after 3 hours. The engineer wants to mark the ticket as resolved with a single comment saying 'Fixed'. What documentation step should be taken? | pass→pass | 7,298 | 5,539 | -24% | 1 | 1 | 0% | 1,347 | 1,141 | -15% | 0 | 0 | — |
▸case-18 A web application works perfectly in the staging environment but throws error 502 in production using identical container images. Developers plan to rewrite the authentication logic. What systematic comparison should be performed? | pass→pass | 12,184 | 11,202 | -8% | 1 | 1 | 0% | 2,266 | 2,031 | -10% | 0 | 0 | — |
▸case-19 A multi-threaded Go application freezes completely under concurrent requests without throwing unhandled panics. Developers suggest adding print statements across all goroutines. What immediate action extracts thread state? | pass→pass | 8,369 | 7,849 | -6% | 1 | 1 | 0% | 1,451 | 1,538 | +6% | 0 | 0 | — |
▸case-21 Convert this legacy ES5 JavaScript file into modern ES6 syntax using arrow functions, destructuring, and async/await syntax. No bugs exist in the working code. | fail→fail | 2,076 | 4,318 | +108% | 1 | 1 | 0% | 306 | 816 | +167% | 0 | 0 | — |
▸case-22 Can you audit our backend code repository and give general code style suggestions? There are no active bugs, crashes, or performance complaints. | pass→pass | 11,372 | 9,599 | -16% | 1 | 1 | 0% | 2,233 | 2,099 | -6% | 0 | 0 | — |