How to adjust HPACK dynamic table?

Jon Carmicheal lemur117 at
Thu Dec 17 05:01:54 UTC 2020

I would like to disable the caching of headers in the dynamic table of the HTTP/2 HPACK compression algorithm described in RFC 7541. I have defined my nginx server with

listen 8080



and I've confirmed that the HPACK algorithm is working as expected with Huffman encoding, static header table indexing, and dynamic header table indexing. But I haven't been able to disable the dynamic table.

RFC 7541 mentions in "Section 4.2. Maximum Table Size" the ability of an HTTP/2 node to "clear entries from the dynamic table by setting a maximum size of 0, which can subsequently be restored." Is that a feature supported by nginx? Can I disable the dynamic table entirely so that no header fields are cached? And can I arbitrarily send a flush request so that all entries are evicted and then the dynamic table size is restored? If so, how?

I've been trying to play with "http2_max_field_size" and "http2_max_header_size" in the server configuration file as described in But I don't think those are the right parameters. When I set either of them to zero, it makes the server return an error when a header is sent.

Thanks for any pointers you can give me.
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