Parallel File Transfers in Rust — How I Made Android Sync Actually Fast

All tests run on an 8-year-old MacBook Air. All results from shipping 7 Mac apps as a solo developer. No sponsored opinion.

Sequential file transfer is slow. HiyokoAutoSync uses parallel transfers with a concurrency limit. Here's how I built it.

The problem with sequential transfer

Copy 100 photos from Android to Mac one at a time: each transfer waits for the previous to complete. ADB overhead per file adds up. On a large library, this takes minutes.

Parallel transfers use the available bandwidth more efficiently. Same 100 files, 6 concurrent transfers: significantly faster.