The scheduler just went public after nine years. meta open-sourced rebalancer, the c++ library it…
the scheduler just went public after nine years. meta open-sourced rebalancer, the c++ library it has used to place shards, servers and traffic across roughly 40 million assignment problems.
most ai infra is now a leaked internal tool.
Context
Meta Engineering announced it is open-sourcing Rebalancer, the assignment-problem solver Meta has used for resource allocation across its infrastructure for over nine years. It assigns objects to bins under constraints and has both an optimal MIP solver and a parallelized local search solver.
MarkTechPost describes it as a C++ solver that runs about 40 million placement problems a day.
Nine years, the C++ library and the roughly 40 million problems match Meta's post and MarkTechPost. The 40 million figure is per day and comes from the coverage.
The note says shards, servers and traffic. Meta lists hardware placement, service and task placement and traffic routing, so 'shards' is unsupported here, not refuted.
'Most ai infra is now a leaked internal tool' is the author's opinion.
Related work
- Meta Engineering announcement ↗Meta's own post, mirrored.
- MarkTechPost ↗The 40 million problems a day figure.
- Softonic ↗The PyPI release.
Watch next
- Read the repo README for the supported problem types.
Sources
- Meta Engineering post, Oct 2026nitter.cf
- MarkTechPost, Oct 6, 2026marktechpost.com
- Softonic, Oct 2026en.softonic.com
Provenance
The note above is reproduced unedited from the original post, first published on Threads on 10 October 2026 at 03:33 IST. Sources are the papers and datasets the note draws on.
View the original post ↗Embed this note
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