JosephJennings

Post-training at xAI, with a focus on evaluations, graders, and infrastructure for coding agents.

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A red footbridge over a turquoise river, with lush summer trees, distant hills, soft clouds, and a sunlit greenhouse on the bank, painted in a classic anime style.

Experience

Robinhood

Software Engineer

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Built evaluations for agentic trading and the Model Context Protocol integration used to place trades. Also worked on Kafka partitioning and PostgreSQL transaction contention for Robinhood’s credit card.

Apple

Graduate Software Engineer Intern

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Built an agent that investigates server failures using trace logs and system-architecture guidelines, then integrated its diagnoses into the server-management interface.

  • Triage agent launched

Sprout Social

Software Engineer II

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Built a feature-flagging service for safer deployments and rollbacks, handling more than 1,200 requests per second.

JPMorgan Chase

Machine Learning Engineer Intern

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Trained a graph neural network on 1.1 million nodes and improved F1 from 0.22 to 0.61 over the XGBoost baseline.

Research

Enhanced Soups for Graph Neural Networks

GrAPL @ IPDPS · 2025

Joseph Zuber, Aishwarya Sarkar, Joseph Jennings, Ali Jannesari

A method for merging independently trained graph neural networks by learning their mixing weights.

arXiv ↗PDF ↗
  • 24.5×souping speedup
  • −76%souping memory
  • +1.2%accuracy, up to
How it works

Mixing weights are fitted on validation data with gradient descent. A partitioned variant merges parameter slices for larger graphs.

Gossip-Based Distributed KV Cache for LLM Inference

Graduate research · University of Illinois

A prototype that shares compressed key-value cache entries between inference replicas. In our test cluster, it reduced P99 latency by 40% and maintained availability with 80% of nodes down.

Reading

Papers & posts

Books

Education

University of Illinois Urbana-Champaign

Master’s in Computer Science

Distributed Systems & Cloud Computing

Iowa State University

B.S. in Computer Science

Teaching assistant: data structures, OOP, Python.

Contact

Say hello.

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The same river and footbridge at sunset, with fireflies over the grass and a red post box beside the path.