IN this article, Cloudflare's team explains how they identified and resolved a bug in the hyper HTTP library, which affected image processing requests through the Images service. The issue manifested as intermittent image data truncation during transformations, returning a `200 OK` status without indicating errors. After extensive debugging, they discovered it was a timing-dependent race condition caused by premature shutdowns of the connection without fully flushing the internal buffer.
A rearchitecture of the service introduced this issue by changing the intermediary service's behavior. The solution involved modifying the hyper library to ensure that data is completely flushed before closing the connection, thus preventing data loss in the future. The fix has been merged into hyper’s main branch and will be included in a future release.