Driftsort

Rust's standard stable sort since 2024, replacing the previous merge sort. Derived from Orson Peters' glidesort, driftsort adds robustness guarantees for production use while maintaining glidesort's performance innovations.

Performance

Glidesort (driftsort's predecessor) achieves up to 4x faster than Rust's previous slice::sort on random data through three key innovations:

• Lazy logical runs — instead of eagerly detecting and extending natural runs (like Timsort), glidesort lazily tracks run boundaries and merges only when beneficial.
• Branchless bidirectional partitioning — eliminates branch mispredictions during the partition phase, a critical bottleneck on modern CPUs.
• Interleaved multi-run merging — merges multiple runs simultaneously, exploiting instruction-level parallelism rather than sequentially merging pairs.

Context in the sorting landscape

Both pdqsort and driftsort were created by Orson Peters (driftsort with Lukas Bergdoll). Peters is responsible for two of the three best sorting algorithms in practical use — an extraordinary contribution.

Python 3.11+ took a lighter-touch approach, replacing only Timsort's merge policy with Powersort for more balanced merge scheduling while keeping the same underlying adaptive merge-sort framework.