Ruby Developer

Job Title: Lead Ruby Developer

Work Location: Chicago, IL

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