Tengine with XQUIC will buffer the entire response body into RAM about tengine HOT 2 OPEN

All read and write events of Tengine operate in Edge-Triggered mode. It is efficient and safe.
The directive proxy_buffering is enabled by default. You can disable the proxy_buffering specifically. Then, the response is passed to a client synchronously.

proxy_buffering                         off;
proxy_buffer_size                     64k;
proxy_buffers                           256 64k;

BTW, if the upstream response with the header "X-Accel-Buffering: no" specifically, even if the Tengine directive "proxy_buffering on" by default, the response will be passed to the client synchronously.

from tengine.

Thanks for the response. In my test case, I was serving a static file from the disk directly with Tengine (using the root directive). I was not using the reverse proxy functionality, so I do not believe that directive will fix the problem. I will try setting proxy_buffering in the test environment.

Additionally, the issue only occurs when using XQUIC. Using the same configuration, I can serve the same file with HTTP/2 and HTTP/1.1 without significant memory increase. I traced the buffering behavior with XQUIC to the function ngx_http_xquic_send_chain in gdb, and I do not believe it is possible to disable it with configuration.

I can provide the full configuration if needed.

from tengine.