Changed keepalive_requests default to 1000 (ticket #2155). It turns out no browsers implement HTTP/2 GOAWAY handling properly, and large enough number of resources on a page results in failures to load some resources. In particular, Chrome seems to experience errors if loading of all resources requires more than 1 connection (while it is usually able to retry requests at least once, even with 2 connections there are occasional failures for some reason), Safari if loading requires more than 3 connections, and Firefox if loading requires more than 10 connections (can be configured with network.http.request.max-attempts, defaults to 10). It does not seem to be possible to resolve this on nginx side, even strict limiting of maximum concurrency does not help, and loading issues seems to be triggered by merely queueing of a request for a particular connection. The only available mitigation seems to use higher keepalive_requests value. The new default is 1000 and matches previously used default for http2_max_requests. It is expected to be enough for 99.98% of the pages (https://httparchive.org/reports/state-of-the-web?start=latest#reqTotal) even in Chrome.

fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
fastcgi_param  QUERY_STRING       $query_string;
fastcgi_param  REQUEST_METHOD     $request_method;
fastcgi_param  CONTENT_TYPE       $content_type;
fastcgi_param  CONTENT_LENGTH     $content_length;

fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
fastcgi_param  REQUEST_URI        $request_uri;
fastcgi_param  DOCUMENT_URI       $document_uri;
fastcgi_param  DOCUMENT_ROOT      $document_root;
fastcgi_param  SERVER_PROTOCOL    $server_protocol;
fastcgi_param  REQUEST_SCHEME     $scheme;
fastcgi_param  HTTPS              $https if_not_empty;

fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
fastcgi_param  SERVER_SOFTWARE    nginx/$nginx_version;

fastcgi_param  REMOTE_ADDR        $remote_addr;
fastcgi_param  REMOTE_PORT        $remote_port;
fastcgi_param  SERVER_ADDR        $server_addr;
fastcgi_param  SERVER_PORT        $server_port;
fastcgi_param  SERVER_NAME        $server_name;

# PHP only, required if PHP was built with --enable-force-cgi-redirect
fastcgi_param  REDIRECT_STATUS    200;