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Keeps cached reads acceptably fresh and prevents hot-key reloads from overwhelming the database across application instances.
Places an idempotency key at the Spring boundary while persisting request identity and terminal outcome atomically with business work.
Coordinates startup work, readiness, schema compatibility, warmup, and mixed-version traffic during a rolling release.
Binds typed configuration, understands property precedence, validates startup invariants, and keeps secrets outside source control.
Carries an original version through an API update and turns an optimistic-lock failure into an explicit conflict workflow.
Reviews correctness, boundaries, failure behavior, capacity, security, observability, delivery, and recovery through concrete evidence.
Sizes per-instance database concurrency from workload and database capacity instead of equating more connections with more throughput.
Uses thread dumps, heap dumps, logger changes, mappings, and configuration evidence through a tightly controlled operator path.
Uses Actuator for operational visibility while controlling endpoint exposure, access, detail, and network reachability.
Builds a small immutable money type with explicit scale, rounding, arithmetic, ordering, and value equality.
Carries the version observed by the client into a conditional update and returns an explicit conflict instead of silently overwriting newer data.
Uses a scoped idempotency key, request hash, unique constraint, and one transaction to create an order exactly once from the API perspective.
Implements descending cursor pagination with a unique tie-breaker, bounded projection query, and next-cursor detection.
Resolves Java's pass-by-value confusion by separating mutation through a copied reference from reassignment of the caller's variable.
Fetches multiple URLs with bounded concurrency, per-request and batch deadlines, cancellation, ordered results, and executor cleanup.
Persists business state and durable publication intent atomically, leaving broker delivery to an idempotent retrying publisher.
Tests anonymous, owner, non-owner, and missing-resource outcomes through the real Spring Security filter chain.
Runs a Spring Boot integration test against PostgreSQL and proves a migration-backed database constraint at flush time.
Explains the request identity model, principal and authorities, default thread-local storage, cleanup, and asynchronous boundaries.
Connects transient, managed, detached, and removed states to persist, merge, dirty checking, and safe update workflows.
Balances faster startup and unused-bean avoidance against delayed failures, first-request latency, memory growth, and readiness semantics.
Explains singleton, prototype, request, session, application, and WebSocket scopes as container lifecycle policies.
Defines races through timing-dependent shared-state operations and evaluates confinement, immutability, synchronization, and atomic tools.
Fixes lazy access outside the persistence context with explicit fetch and DTO mapping while explaining the tradeoff of Open Session in View.