Compiler Reliability Engineer


The Multicore OCaml project aims to add native support for scalable concurrency and shared memory parallelism to the OCaml programming language. At its core, Multicore OCaml extends OCaml with effect handlers for expressing scalable concurrency, and a high-performance concurrent garbage collector aimed at responsive networked applications. Multicore OCaml is also the first industrial-strength language to be equipped with an efficient yet modular memory model, allowing high-level local program reasoning while retaining performance.

Multicore OCaml is actively being developed and core features are being upstreamed to OCaml. The multicore project at Tarides is a close collaboration with our industrial partners OCaml Labs and Segfault Systems.

As we get closer to releasing OCaml 5.0 with Multicore support, there is a need to ensure that the multicore support works well with the rest of the ecosystem. The ecosystem includes the open-source tools and libraries maintained by the Multicore team as well as the wider ecosystem. We have built a number of tools to assist with the task at hand. Some of the tools are:

  • OPAM Health Check shows the result of building the packages from the OPAM repo. The table shows the result of building the package and running its opam tests (if present) on the stock OCaml compiler and the domains-only version of the multicore compiler. Any failure in the multicore column with a success in the stock column must be investigated.
  • Multicore OCurrent CI tests a matrix of blessed packages that the multicore team considers important for the ecosystem. Unlike OPAM health check, the packages and the compiler variants may be unreleased and part of other development branches in GitHub. This tool builds the workflow as a dependency graph of individual build tasks. The individual tasks will be rebuilt on demand when the corresponding item being tracked (say the branch on GitHub) is updated.


As a compiler reliability engineer, your tasks will include:

  • Investigating failures thrown up by OPAM Health Check monitoring and deeper package testsuite runs with multicore. Determine if the issue is a problem for the package maintainer or the multicore compiler.
  • File issues and work with the relevant team (external or multicore) to get it fixed by producing reproducible test cases possibly even identifying the subsystem where the problem is occurring.
  • Help organise and link ocaml-multicore bug reports such that issues are correctly linked or merged.
  • Provide support to the multicore team in understanding which bugs and/or features external packages require in order to function well.
  • Work with the rest of the CI team to ensure that the multicore CI systems are running as expected.

Qualifications & Experience

(You don’t have to fill 100% of the qualifications to apply.)

  • Demonstrable experience with existing open source projects
  • Ideally some level of experience with the OCaml language, or other functional programming languages
  • Experience with GitHub, Git and version control
  • Ideally some experience with the OCaml platform ecosystem e.g. dune, opam
  • Domain knowledge relevant to the projects - package management, CI and build environments, developer workflow and processes
  • Curious and solution-oriented mindset
  • Experience of working within multidisciplinary and remote teams
  • Good communication skills in English (English is the corporate language)

What we offer

  • Competitive pay and benefits package.
  • Flexible working hours and the possibility to work remotely worldwide.
  • Supportive team environment with experienced Technical and Team Leads.
  • The opportunity to grow with a fast-growing company.


Please send your CV and cover letter to If shortlisted, you will have three online interviews starting with a general interview, followed by a technical interview, and finally an interview with the team.

We welcome applications from people of all backgrounds. We strive to create a representative, inclusive and friendly team, because we know that different experiences, perspectives and backgrounds make for a better workplace.