9x Technology Llc

Role & responsibilities Senior C++/PostgreSQL API Engineer (Ultra-Low Latency Trading) Location: Hybrid/Remote Type: Full-time Team: Core Trading Platform What youll do Design and build ultra-low-latency C++ services for order routing, market data, and risk checks (targets: p99 500s per hop on LAN; end-to-end trade path p99 3–5ms depending on venue). Implement high-performance APIs (gRPC/Protobuf and WebSocket/REST where needed) exposing trading, positions, and account data backed by PostgreSQL. Engineer lock-free / wait-free components, efficient memory management (arena allocators, object pools), and NUMA-aware data structures. Build and tune PostgreSQL for low-latency reads/writes: schema design for time-series/partitioned tables, prepared statements, libpq/libpqxx, PgBouncer pooling, logical replication, and LISTEN/NOTIFY for eventing. Use Redis (Cluster) for hot paths: price cache, order state cache, Streams/PubSub, Lua scripts for atomic ops; set correct persistence (RDB/AOF) policies per service. Optimize network I/O (epoll/kqueue, io_uring), batching, zero-copy, and back-pressure. Explore kernel-bypass/RDMA/DPDK where justified. Create observable systems: high-resolution latency histograms, tracing, and metrics (Prometheus/Grafana); integrate eBPF or perf for hotspots. Ensure resilience & correctness: deterministic simulations, soak/chaos tests, replay tools from pcap/logs, and circuit-breakers/timeouts. Collaborate with quant, infra, and frontend teams; participate in on-call rotation for production trading hours. Tech you’ll use C++20/23, STL, atomics, chrono, coroutines; Boost.Asio/Folly/absl (as needed); CMake; clang/gcc; sanitizers; valgrind; perf/eBPF; flamegraphs. PostgreSQL 14+, libpq/libpqxx, PgBouncer, partitioning, BRIN/B-tree indexes, COPY, logical replication/decoding. Redis (Cluster/Sentinel), Streams, Pub/Sub, Lua, pipelining. Protocols: FIX (nice-to-have), exchange/venue native, Protobuf/gRPC, WebSocket/HTTP/2. Tooling: Git, CI/CD, Docker/Podman; Kubernetes (nice-to-have). Minimum qualifications 5+ years with modern C++ in production, including low-latency and concurrency (lock-free, ring buffers, SPSC/MPSC queues). Deep knowledge of Linux systems: CPU pinning, NUMA, cache lines/false sharing, NIC tuning, kernel params. Strong PostgreSQL experience: performance tuning (autovacuum, WAL, checkpoint, shared_buffers), query planning, prepared/batched I/O. Production Redis usage for latency-critical paths (pipelining, key design, eviction strategy). Profiling + benchmarking mindset; you’ve moved p99s not just averages. Nice-to-have Market data/order-book engineering (price-time priority, gap handling, snapshot+incremental models). Risk/limits engines (per-account, per-symbol throttles), idempotent order handling. Experience with FIX, Betfair/sportsbook APIs or crypto exchange APIs. Hardware timestamping/PTP, NIC offloads; DPDK/Netmap; io_uring; RDMA. Kafka/NATS/Chronicle Queue; columnar/time-series DBs (ClickHouse, Timescale). Success metrics (first 90–180 days) Reduce critical service p99 latency by 30%; eliminate GC/allocator spikes. Achieve zero order-path correctness defects in production releases. Establish automated latency SLO dashboards and regression benchmarks in CI. Deliver a new C++ trading API with Postgres+Redis backing that sustains >50k msgs/sec with p99 under target on staging hardware. Sample problems you’ll tackle Re-architect order ingress with batched syscalls + lock-free queues to cut tail latency. Redesign Postgres schemas to partition by (symbol, day); add BRIN for time scans; switch to prepared multi-row INSERTs. Introduce Redis Streams for fast, ordered state fan-out with consumer groups. Add exact-once semantics across C++ Redis Postgres using idempotency keys and outbox/inbox patterns.