Job Description
This requirement is with our Client - Fujistu. we have 8 positions Key Responsibilities & Required Technical Expertise: Strong Expertise with Ruby Minimum 12 years of experience on Ruby Deep knowledge of Ruby MRI internals (GIL, memory model, object allocation) Ruby MRI garbage collector (mark & sweep, generational GC) Strong experience with Rails internals (ActiveRecord, Arel, middleware stack) Ability to optimize slow queries, N+1 issues, and memory leaks Experience with multi-threaded / concurrent Ruby (Puma, Sidekiq tuning) Ruby VM instruction set (YARV bytecode basics) Concurrent Ruby gem Thread pools vs Fibers vs Ractors Async frameworks (Falcon / Async gem) Experience integrating Ruby with Kafka (ruby-kafka / Karafka), exactly-once semantics handling Designing: event schemas, schema evolution (Avro / JSON schema) Proven experience scaling Rails apps to: 10K+ RPS millions of daily transactions Hands-on experience with: Event-driven architecture (Kafka / RabbitMQ) CQRS & Event Sourcing Saga pattern (choreography & orchestration) Strong understanding of Eventual consistency Distributed transactions Idempotent APIs Deep understanding of Caching strategies (Redis, Memcached) Background processing (Sidekiq, Resque) Database sharding and read replicas Strong experience with PostgreSQL (query tuning, indexing, vacuum, locking) Redis (data structures, pub/sub, distributed locks) Ability to debug deadlocks slow queries replication lag Low-Latency / High-Throughput Optimization Experience achieving o sub-50ms API latency under load o High throughput using connection pooling, query batching Hands-on tuning: o Puma workers vs threads trade-offs o kernel tuning (ulimits, TCP tuning) Deep Sidekiq Internals Queue prioritization strategies Dead job recovery idempotent job design Redis contention debugging Sidekiq middleware customization Experience with AWS (EKS, RDS, SQS, Lambda) Docker & Kubernetes CI/CD pipelines (GitHub Actions / Jenkins) Observability stack: o Prometheus o Grafana o ELK / OpenSearch OAuth2 / JWT authentication PCI-DSS exposure (preferred) Secure API design (rate limiting, mTLS, encryption) Experience working at high-frequency trading firms payment processors crypto exchanges JRuby / TruffleRuby GraphQL APIs gRPC services Exposure to fraud detection systems real-time risk engines