Hello! On Mon, Feb 25, 2019 at 09:46:56PM +0800, yf chu wrote:
> But if a connection to upstream is dead or there are some other > network problems in this connection, how could Nginx handle it, > will the HTTP requests on this connection be affected? For > example, is it possible that the HTTP requests on this > connection is hanging until timeout? If a connection is silently dead, nginx will have to wait till a relevant timeout expires. If a network error occurs, nginx will be able to detect this and will act accordingly. If a network error or timeout occurs when re-using a keepalive connection, nginx will retry a request as per proxy_next_upstream (and will allow an additional retry attempt to make sure even requests to a single upstream server a retryed). Note this doesn't really depend on using keepalive connections, as well as keepalive_requests and keepalive_timeout directives. Though some network problems may become more obvious when using keepalive connections. In particular, a statefull firewall between nginx and a backend can be a problem if states are dropped after some inactivity timeout, and using keepalive_timeout may help to mitigate such problems (though using proxy_socket_keepalive or removing the firewall might be a better way to go). The main goal of the keepalive_timeout directive is to avoid the race between closing of a connection by the upstream server and using this connection for another request, most importantly in case of non-idempotent requests which cannot be retried. The main goal of the keepalive_requests directive is to make sure connections will be closed periodically and connection-specific memory allocations will be freed. -- Maxim Dounin http://mdounin.ru/ _______________________________________________ nginx mailing list nginx@nginx.org http://mailman.nginx.org/mailman/listinfo/nginx
