John Heemstra Email & Phone Number

Houston, Texas, Us

Linux kernel driver development for Slingshot.

Houston, Texas, Us

Tech lead for the group responsible for the initial bare-metal deployment of the Kubernetes-based management cluster for HPE Cray EX Supercomputers.

Springfield, Massachusetts, Us

Tried Fintech. Didn't enjoy it. Learned that I much prefer an engineering environment and mindset.

Houston, Texas, Us

Architect for CI/CD/CT within the Cray business at HPE. Responsible for defining the continuous development pipeline strategy and setting the technical direction for its implementation.

Houston, Texas, Us

Hands-in-code Software Engineering Technical Manager responsible for Continuous Deployment, Install, and System Administration (internal systems) for Cray's next-generation Shasta product line. Coding work was mostly ansible, python, and bash.Reported internal system status daily to VP and SVP-level technical leadership.Worked remotely from Michigan with 25-35% on-site time in Bloomington, Minnesota.

Houston, Texas, Us

Senior engineer working on Continuous Deployment and install.

Hood River, Oregon, Us

Versity is a small company with a start-up mentality and start-up staffing levels. As such my responsibilities at Versity were varied and changed rapidly depending on the needs of the company at any given time. Following are some of the activities that were primarily or solely my responsibility:One of three developers writing new features, written in Python, for a next-generation scale-out archive storage manager.Development of an installer for Versity's next-generation storage manager.Development of automated testing tools, written in bash, Ansible, and Python. This work included writing extensive bash and Ansible for booting test nodes (ec2 and internal VMs, depending on the test needs), installing software on the nodes, running the tests, and automatically collecting crashdumps and other diagnostics on error. These tools can be driven by a CI/CD application such as Travis or Jenkins, or directly by a developer.Various infrastructure work related to keeping internal VMs, Docker services, and the company VPN running smoothly.Relevant technologies and methodologies I interacted with at Versity: Ansible, AWS, DevOps, Docker, GitHub, Python, Travis, S3.Worked remotely from Michigan.

Houston, Texas, Us

Progressed from a junior software engineer to the lead software engineer for the high-speed network driver for the Cray XT3/XT4/XT5. In this role I engineered two major changes to the networking driver: the first major change migrated the multiprocessing implementation from a single global lock to fine-grained locking. The second major change involved modifying the underlying firmware to direct RX interrupts to the CPU core responsible for handling that RX, then handling that in the Linux kernel driver for the high-speed NIC. Without these major changes, the Jaguar supercomputer at Oak Ridge National Laboratory would not have become the fastest computer in the world in 2009.Overhauled the internal software triage process, taking it from a rotating duty amongst most software engineers to a role owned by one or two individuals. While doing so, developed a PHP/MySQL interface for managing triage incidents instead of the antiquated method of handling it all via email. (2024 edit: 16 years later, this internal website tracked its last triage incident.)Implemented the initial support for Cray's MPI on Intel's Knight's Corner architecture.Performed software support services for Cray's largest installations and most important customers.Worked remotely from Michigan.

Colorado Springs, Colorado, Us

Developed low-level Java methods for interfacing with network devices such as managed switches and load balancers. These Java methods interfaced with Expect scripts that were used to log into the various network devices. Designed XML files that were used as configuration files describing available network devices.Worked remotely from Michigan.

Spent most of my time working on hardware/interconnect-specific job startup architecture for MPI.Worked remotely from Michigan.

Operating System testing. MPI development (initial port of SGI's MPI to the Cray X1).

Milpitas, Ca, Us

Wrote tests for MPI and the IRIX operating system. Ran tests, evaluated results, filed bugs.

Houghton, Mi, Us

Student residential tech support for both the Ethernet and CATV networks, including installations and troubleshooting.Monitored MTU newsgroups for the purpose of addressing concerns related to student use of the campus network.Assisted with faculty training on topics such as web page development, including authoring documentation for the training.

Bachelor Of Science, Computer Science

Engineering