Http2SecureServer.close fails

[aabfred]

• Version: v9.10.1
• Platform: Linux Host-001 4.14.6-300.fc27.x86_64 deps: update openssl to 1.0.1j #1 SMP Thu Dec 14 15:31:24 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
• Subsystem: http2

Problem:
Closing an Http2Server runs only when it has no connection;
Otherwise, no "close" or "error" event is emitted after close(), and script doesn't exit (server still listening)

bug.js:
const
http2 = require( "http2" ),
srv = http2.createServer();
srv.listen(9000);
const client = http2.connect("http://localhost:9000");
setTimeout(() => { srv.close() }, 500);

$ export NODE_DEBUG=http2; node ./bug.js
HTTP2 30406: Http2Session client: created
(node:30406) ExperimentalWarning: The http2 module is an experimental API.
HTTP2 30406: Http2Session server: received a connection
HTTP2 30406: Http2Session server: setting up session handle
HTTP2 30406: Http2Session server: sending settings
HTTP2 30406: Http2Session server: submitting settings
HTTP2 30406: Http2Session server: created
HTTP2 30406: Http2Session client: setting up session handle
HTTP2 30406: Http2Session client: sending settings
HTTP2 30406: Http2Session client: submitting settings
HTTP2 30406: Http2Session client: new settings received
HTTP2 30406: Http2Session server: new settings received
HTTP2 30406: Http2Session server: settings received
HTTP2 30406: Http2Session client: settings received

[anliting]

Maybe it is not a bug: "Stops the server from accepting new connections and keeps existing connections." (from https://nodejs.org/api/net.html#net_server_close_callback)

[aabfred]

Http2Server.close() has not the same behaviour as HttpServer.close() and HttpsServer.close().
I'm not opposed to this idea, it sould then be explicit in http2 docs.

[anliting]

I think they have the same behavior, consider:

import http from 'http'
let sv=http.createServer((rq,rs)=>{})
sv.listen(8000)
let rq=http.get('http://localhost:8000/',rs=>{
    sv.close()
})

[lpinca]

http2.createServer() and http2.createSecureServer() return respectively an instance of Http2Server and Http2SecureServer which inherit from net.Server and tls.Server so it is somehow implied that the close method work in the same way and has the same behavior.

That said, it doesn't harm to clarify that in the docs.

[anliting]

I would guess @aabfred is new to HTTP/2. Would you like to figure the differences out, and describe the illusion that they don't have the same behavior? I think it might help making a good documentation.

[chrismilleruk]

Hi, I'm interested in making some improvements here if this is available?

I noticed that inherited methods such as close don't appear in the HTTP2 docs, is that a deliberate style-guide convention or is it OK to add these in with a suitable footnote?

I also thought it might be worth introducing a brief explainer near the top to cover the most obvious differences (i.e. introduction of sessions and streams). Would be keen to hear thoughts on this.

[chrismilleruk]

OK, PR sent. I've kept it simple for the moment but I have enough context now that I can add more details if needed.

The perceived behaviour seems to be that server.close() would result in process termination within a reasonable timescale. This is true for HTTP/1 where connections and requests have a reasonably close relationship but less true for HTTP/2 where connections are persistent and clients are encouraged to keep them open for long periods.

I think that calling http2Session.close() on all active sessions will help to gracefully close open sockets so I made a suggestion in the footnotes but I may be wrong (looking to validate this).

💭 if calling session.close() on all children is a common use case, perhaps this should be default behaviour? I saw a mention of an http2.Pool object in #17746 that might make this easier to implement.