Index prefetch packs in parallel #1843
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#1840 required local indexing of pack files (an expensive task for large repositories) to
gvfs clone. This pull request improves the performance of pack file indexing by:git index-packinstances asynchronously during prefetch, andgit index-pack, overriding the git default of half the processor count.The prefetch API will usually return one large pack file comprising most of the commits and trees, followed by several smaller pack files representing the new commits and trees since the last maintenance job consolidated the main pack file.
git index-packbegins with a single-threaded task to index the objects in the pack file, followed by a multi-threaded task to resolve the deltas. With these changes, the smaller incremental pack files are typically indexed in full while the primary pack file is still in its single-threaded phase, and the primary pack file's multi-threaded phase is marginally faster.In testing, these changes reduced clone time for a large repository by 15-30%.