I originally filed this as seanmonstar/reqwest#1761 : Downloading https://chromium-browser-symsrv.commondatastorage.googleapis.com/chrome.dll.pdb/93B17FC546DE07D14C4C44205044422E1/chrome.dll.pdb with h2 stalls after around 360MB. The stall appears to be caused by an unfortunate interaction h2's flow control behavior and the server's behavior.

I've put a full reproduction here: https://github.com/mstange/reqwest-with-rusttls-stops-after-360mb , specifically in this file:

https://github.com/mstange/reqwest-with-rusttls-stops-after-360mb/blob/main/variant-4-h2-direct/src/main.rs

Steps to reproduce:

git clone https://github.com/mstange/reqwest-with-rusttls-stops-after-360mb && cd reqwest-with-rusttls-stops-after-360mb
cd variant-4-h2-direct/
cargo run --release

Expected results:

The program should complete and print Done! Downloaded 639588034 bytes in total.

Actual results:

The program stops downloading after around 360MB. It will print Error: No new data for 5 seconds! once it detects a stall.

Configuration

• h2 v0.4.12
• window sizes: 2MB stream, 5MB connection (the goal was to match the hyper defaults)
• macOS 15.6.1, Rust 1.89.0