The config `proxy.config.io.max_buffer_size` determines the default Max IOBuffer size that's used when the caller (e.g HostDB alloc, POST request buffer) asks for a chunk of memory via the `iobuffer_size_to_index()` or `buffer_size_to_index()` interfaces without explicitly passing in the max IOBuffer. This can cause issues such as https://github.com/apache/trafficserver/issues/6850 or worse memory corruption such as https://github.com/apache/trafficserver/issues/6849 After some discussion with Leif, we think we should let callers explicitly pass in the max buffer sizes when asking for unknown sized memory chunks (e.g proxy.config.http.max_post_size and a new config proxy.config.hostdb.max_buffer.size) and remove the hidden default max io config.
Please let us know if there are any concerns/comments.
