Hello,
But I feel the need to continue this discussion because I have zero load, just me on localhost and I see rate limiter (anti DOS) in effect. To my understanding, I must _only_ see it when server is under considerable load from one connection, which is not the case.
Just couple of days ago I switched to Embedded Jetty and enabled HTTP/2. While testing all this on localhost, not only I get these exceptions in the logs, but they also affect web application - HTTP requests are dropped and static resources are never fetched. It happens very randomly and often.
So, main exception is (example):
(HttpChannel.java:596) - handleException /images/social-buttons/share.png java.io.IOException: enhance_your_calm_error/invalid_priority_frame_rate
Chrome Developer Tools Status column says:
(failed)net::ERR_HTTP2_PROTOCOL_ERROR
Sometimes they occur both and sometimes I get the (failed) in Chrome Dev Tools but I see no exception in logs.
I use:
Spring Boot 2.3.4 and from the dependencies I see that Jetty 9.4.31 is in use. My relevant Gradle part:
implementation 'org.springframework.boot:spring-boot-starter-jetty'
implementation 'org.eclipse.jetty:jetty-alpn-conscrypt-server'
implementation 'org.eclipse.jetty.http2:http2-server'
No other Jetty-specific configurations are made. Just these common server properties:
server.http2.enabled=true
server.compression.enabled=true
server.compression.min-response-size=1024
plus server.ssl.* configuration.
So, I am writing this to clarify/ask several things:
1) Since that initial question was asked a year ago, today that default is still 20 events per second, that means the team behind Jetty thinks that this is a reasonable default. But at the same time, I don't think that I should see HTTP requests dropped with this limit being the only user on localhost without any load. So, something is not quite right, please clarify.
2) A lot of settings in Jetty are in INI file, including this configuration jetty.http2.rateControl.maxEventsPerSecond
but I am using Embedded Jetty, I don't have access to INI. I've searched everywhere on how to set it but found nothing. Common Spring server-prefixed properties do not expose it. Jetty prefixed properties do not expose it. Setters on HttpConfiguration, ServerConnector, etc. do not exist. By digging Jetty source code, I know I can manually create implementation of AbstractHTTP2ServerConnectionFactory, but I'd rather not, because it's not transparent how to do it properly. I'd rather rely on standardized setters or app properties.
My current solution is find currently existing connection factory and set (override) rate control factory, something like this (simplified code):
AbstractHTTP2ServerConnectionFactory http2ServerConnectionFactory = (server.getConnectors()[0]).getConnectionFactories()
.stream()
.filter(it -> it instanceof AbstractHTTP2ServerConnectionFactory)
.map(it -> (AbstractHTTP2ServerConnectionFactory)it)
.findFirst().get();
http2ServerConnectionFactory.setRateControlFactory(new WindowRateControl.Factory(40));
as you can see I set 40 instead of 20, and I don't create new connection factory, but rather look up the existing one, since it's the one which is configured with a value of 20.
After I did this change, I saw no exceptions, but I only tested it several times. I just do not think it is normal that such configuration needs to be made out of the box. Either 20 is a too small value, or I am missing something. But I am observing this behavior with just a single page load, and not all resources get downloaded.
I'd appreciate it very much if you guided me here. I would like to stay with Jetty but this bothers me, as it will affect customers immediately.
