Java app broken in production.Fixed this session.

PM assigned in 10 minutes, Java engineer begins diagnosis within the hour. Spring Boot 500s are most often caused by: a bean initialization failure due to missing environment variable or misconfigured @Value binding, a NullPointerException in a @Service method where a lazy-loaded Hibernate entity was accessed outside a transaction, or a failed Flyway migration leaving the schema in an inconsistent state. The engineer pulls your application logs, checks Actuator /health and /env endpoints, and traces the exact stack frame. Most Spring Boot 500 incidents are resolved within a single 4-hour session.

Yes. JVM heap OOM under load is almost always a heap sizing misconfiguration combined with a memory leak. The engineer captures a heap dump using jmap or the JVM flag -XX:+HeapDumpOnOutOfMemoryError, loads it in Eclipse MAT or VisualVM to identify the dominator objects, and traces the leak to its root cause - commonly: an unbounded cache backed by a HashMap, a ThreadLocal not cleared after request completion, or Hibernate first-level cache accumulating entities in a batch processing loop. The fix includes both patching the leak and right-sizing -Xmx and -Xms for your actual workload. GC tuning (G1GC vs ZGC) is included if the GC pause pattern contributed to the OOM.

Yes. N+1 query problems in Hibernate are diagnosed using Hibernate statistics (spring.jpa.properties.hibernate.generate_statistics=true) combined with a slow-query log or APM trace showing dozens of SELECT statements per parent record. The root cause is almost always a @OneToMany or @ManyToOne association with FetchType.LAZY being accessed in a loop without a JOIN FETCH or @BatchSize annotation. The engineer identifies the offending entity graph, rewrites the JPQL to use JOIN FETCH or a DTO projection query, or applies @EntityGraph to the Spring Data repository method. Query count typically drops from hundreds to single digits per request.

Maven build failures in CI that pass locally are caused by: missing settings.xml credentials for a private Nexus or Artifactory repository, a SNAPSHOT dependency that is being resolved to a different version in the local cache vs the remote, a compiler source/target mismatch between the JDK on the developer machine and the CI container image, or a test that depends on local file system state or a specific timezone not present in the CI environment. The engineer inspects the CI log for the first failure line, reproduces it in a clean Maven local repository (mvn -U clean install), and isolates the environment delta. Build determinism is enforced by pinning dependency versions and fixing the JDK version in the CI image.

Every QuickHire Java engineer passes: a live debugging exercise on a broken Spring Boot application with a hidden Hibernate lazy-loading bug and a JVM memory leak, a written assessment covering Java concurrency (synchronized, ReentrantLock, CompletableFuture), Spring internals (bean lifecycle, AOP proxy mechanics, transaction propagation), and JVM tuning (GC algorithms, heap regions, JIT compilation), plus a portfolio review of production Java services. Only the top 3% of applicants pass. PM matches engineers to your exact stack - Spring Boot version, ORM (Hibernate vs MyBatis), build tool (Maven vs Gradle), and deployment target (EC2, ECS, Kubernetes).

QuickHire Instant is built for immediate engineering execution - book a vetted developer and dedicated PM in under 10 minutes, pay per session with no contracts. QuickHire Enterprise is for long-term team partnerships: dedicated developers, managed engineering pods, staff augmentation at scale, and enterprise-grade contracts (MSA, NDA, SLA) with a dedicated account manager. Both models use the same vetted talent network. Visit enterprise.quickhire.services to explore Enterprise engagements.