Lead Ruby Developer

• 12+ years of strong 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: o 10K+ RPS o millions of daily transactions • Hands-on experience with: o Event-driven architecture (Kafka / RabbitMQ) o CQRS & Event Sourcing o Saga pattern (choreography & orchestration) • Strong understanding of: o Eventual consistency o Distributed transactions o Idempotent APIs • Deep understanding of: o Caching strategies (Redis, Memcached) o Background processing (Sidekiq, Resque) o Database sharding and read replicas • Strong experience with: o PostgreSQL (query tuning, indexing, vacuum, locking) o Redis (data structures, pub/sub, distributed locks) • Ability to debug: o deadlocks o slow queries o replication lag o 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: o Queue prioritization strategies o Dead job recovery o idempotent job design o Redis contention debugging o Sidekiq middleware customization • Experience with: o AWS (EKS, RDS, SQS, Lambda) o Docker & Kubernetes o CI/CD pipelines (GitHub Actions / Jenkins) • Observability stack: o Prometheus o Grafana o ELK / OpenSearch o OAuth2 / JWT authentication o PCI-DSS exposure (preferred) o Secure API design (rate limiting, mTLS, encryption) • Experience working at: o high-frequency trading firms o payment processors o crypto exchanges o JRuby / TruffleRuby o GraphQL APIs o gRPC services • Exposure to: o fraud detection systems o real-time risk engines