On Tuesday 25 June 2013 12:51:17 Yury Kirpichev wrote: > Hi Nginx Developers, > > > Could someone explain what is the purpose to use blocked frame for > SYN_REPLY frame in spdy implementation? > > According to our investigation it makes it impossible to use spdy > priorities because of blocked frames (since each stream is started with > SYN_REPLY which is blocked there is no way how frames from subsequent > requests can outrun previous request with lower priority in spdy output > queue). > [...]
SPDY uses zlib compression for output headers in SYN_REPLY frames. In fact zlib is just a wrapper over deflate compression that consists of LZ77 and Huffman coding. Both client and server must keep LZ77 window in sync between each other across a whole SPDY session, so the order of SYN_REPLY frames cannot be changed after the compression has done. There is a way to improve things a bit. We may postpone compression to the latest phase (right before sending of queue), but it requires more code and we have no ETA for this yet. wbr, Valentin V. Bartenev _______________________________________________ nginx-devel mailing list nginx-devel@nginx.org http://mailman.nginx.org/mailman/listinfo/nginx-devel
