"Reset by peer connection" when mapping a simple Rust HTTP server to ab

Question

I am trying to write an extremely simple parallel server in Rust to play with the concurrency primitives and its thread model. Here is my code:

use std::io::prelude::*; use std::io::Result; use std::net::{TcpListener, TcpStream, Shutdown}; use std::sync::{Arc, Mutex}; use std::thread; fn handle_client(mut stream: TcpStream) -> Result<()> { try!(stream.write(b"HTTP/1.0 200 OK\r\nContent-Type: text/plain\r\nContent-Length: 5\r\n\r\nPong!\r\n")); // try!(stream.shutdown(Shutdown::Both)); Ok(()) } fn main() { let listener = TcpListener::bind("127.0.0.1:1337").unwrap(); // let count = Arc::new(Mutex::new(0)); for stream in listener.incoming() { match stream { Ok(stream) => { // let count = count.clone(); thread::spawn(move || { let _ = handle_client(stream); // let mut count = count.lock().unwrap(); // *count += 1; // println!("{:?}", *count); }); } Err(e) => { println!("Error: {}", e); } } } drop(listener); } 

When I run ab -c 100 -n 100 http://127.0.0.1:1337/ with the program running, as indicated above, I get apr_socket_recv: Connection reset by peer (104) almost immediately. Why?

When I add try!(stream.shutdown(Shutdown::Both)); (commented out near the top, above), I no longer get the apr_socket_recv error as before, but apachebench gives me results that tell 199 failed requests due to exceptions. What for? What am I doing wrong?

 Concurrency Level: 100 Time taken for tests: 0.008 seconds Complete requests: 100 Failed requests: 199 (Connect: 0, Receive: 0, Length: 0, Exceptions: 199) Total transferred: 500 bytes 

Answer 1

I believe that the problem is that you are not completely reading the data sent from the client, so the client will never have the opportunity to proceed to read the response. When he tries to write more data, he notices that the socket has been closed and is not working.

I added your example to read all HTTP headers before the response, ignoring any request body. I do a thorough error handling and just panic if there are errors:

 use std::io::prelude::*; use std::io::BufReader; use std::net::{TcpListener, TcpStream}; use std::thread; fn handle_client(mut stream: TcpStream) { // Read all the headers for header in BufReader::new(&mut stream).lines() { let header = header.unwrap(); if header == "\r" { break } } // Write our response stream.write_all(b"HTTP/1.0 200 OK\r\n\r\n").unwrap(); } fn main() { let listener = TcpListener::bind("127.0.0.1:8080").unwrap(); for stream in listener.incoming() { let stream = stream.unwrap(); thread::spawn(|| { handle_client(stream); }); } } 

This works with ab -c 50 -n 5000 http://127.0.0.1:8080/ :

 Benchmarking 127.0.0.1 (be patient) Completed 500 requests Completed 1000 requests Completed 1500 requests Completed 2000 requests Completed 2500 requests Completed 3000 requests Completed 3500 requests Completed 4000 requests Completed 4500 requests Completed 5000 requests Finished 5000 requests Server Software: Server Hostname: 127.0.0.1 Server Port: 8080 Document Path: / Document Length: 0 bytes Concurrency Level: 50 Time taken for tests: 1.293 seconds Complete requests: 5000 Failed requests: 0 Total transferred: 95000 bytes HTML transferred: 0 bytes Requests per second: 3868.22 [#/sec] (mean) Time per request: 12.926 [ms] (mean) Time per request: 0.259 [ms] (mean, across all concurrent requests) Transfer rate: 71.77 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 1 6 1.7 6 14 Processing: 1 6 1.7 6 14 Waiting: 1 6 1.7 6 14 Total: 5 13 2.6 12 23 Percentage of the requests served within a certain time (ms) 50% 12 66% 13 75% 13 80% 14 90% 17 95% 19 98% 21 99% 22 100% 23 (longest request) 

Answer 2

The TcpStream documentation states that

The socket will be closed when the value is reset.

Since your function ends without properly disconnecting the TCP stream, but just closing the socket, you get a Connection reset by peer error. Full TCP shutdown requires sending multiple messages in both directions. This obviously cannot be, since the socket was closed.

I have no answer to your second question. In addition, in stackoverflow you should only ask one question per question.