> On Apr 12, 2021, at 2:04 PM, Christopher Schultz > <ch...@christopherschultz.net> wrote: > > Mark, > > On 4/12/21 04:16, Mark Thomas wrote: >> maxHttpHeaderSize only applies to Tomcat reading requests from clients. It >> has no impact on the headers Tomcat sends to the client. >> Given that the issue is size dependent and the the header is missing only on >> the larger responses, I would guess that the Servlet is writing the header >> after the response has been committed in those cases and is, therefore, >> being lost. >> In HTTP, headers usually come before the body. When generating a response, >> Tomcat will buffer the response body until either there is an explicit flush >> or explicit commit or the buffer is full at which point an implicit flush >> occurs. >> When a flush (implicit or explicit) occurs, if the response is not committed >> at that point then the response is automatically committed. Committing the >> response == writing the response headers. >> You typically want to ensure that the Servlet writes all the headers before >> it writes the response body. >> There are alternative options: >> 1. Use a large enough response buffer to buffer the entire response. Keep in >> mind you need to have enough free memory for every concurrent request to >> have a buffer this large whether it uses it or not. >> 2. Servlet 4 (Tomcat 9 onwards) added support for trailer headers (see RFC >> 7230 section 4.4). These can be used with chunked encoding and allows header >> values to be written after the response body. You might want to confirm that >> the client you are using supports trailer headers. > > Notably the HttpClient client class provided by Java 9+ *does* support > trailers in the response from the server. Unfortunately, it doesn't support > sending trailers *to* the server, which is a shame. > > -chris
I can live with to-client only! Now to figure out the setting. Thanks all. > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > <mailto:users-unsubscr...@tomcat.apache.org> > For additional commands, e-mail: users-h...@tomcat.apache.org > <mailto:users-h...@tomcat.apache.org>
