Why reading from a socket stream blocks forever?

Question

I'm trying to do some HTTP manually by opening a TCP socket, send the request and read/print the response message. The content of the response body is well printed , but the main thread never exits and blocks forever.

socket = new Socket(host, port);
PrintWriter writer = new PrintWriter(socket.getOutputStream());
writer.print(request);
writer.flush();
BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
reader.lines().forEach(System.out::println);
// String next_record = null;
// while ((next_record = reader.readLine()) != null)
// System.out.println(next_record);

socket.close();
// System.out.println("Finished");

What am I missing, and how can I fix it ?

Ep, seems to be something for what `Lambdas` are not good for ;-) — PeterMmm, Mar 27 '14 at 15:14
@PeterMmm No, the problem has nothing to do with lambdas, I just trying to keep the code clean and readable. — Salah Eddine Taouririt, Mar 27 '14 at 15:18

score 2 · Accepted Answer · answered Mar 27 '14 at 15:59

Are you making sure you're sending the HTTP request correctly? This works for me. Note the "Connection: Close\r\n" string was important otherwise it hangs for me too after reading the content.

import java.net.Socket;
import java.io.PrintWriter;
import java.io.*;

public class App {

    public static void main(String[] args) throws Exception {
        String host = "google.com";
        int port = 80;
        Socket socket = new Socket(host, port);

        //BufferedWriter writer = new BufferedWriter(
        //       new OutputStreamWriter(socket.getOutputStream(), "UTF-8"));
        PrintWriter writer = new PrintWriter(socket.getOutputStream());
        writer.write("GET / HTTP/1.1\r\n");
        writer.write("Connection: Close\r\n");
        writer.write("\r\n");
        writer.flush();

        BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream(), "UTF-8"));

        // reader.lines().forEach(System.out.println);
        String line;
        System.out.println("Reading lines:");
        while ((line = reader.readLine()) != null) {
            System.out.println("* " + line);
        }
        System.out.println("DONE READING RESPONSE");

        reader.close();
        writer.close();
        // socket.close();

        System.out.println("Finished"); 
    }

}

You are sending an HTTP 1.1 request, so the server is free to send a `chunked` response if it chooses to. See [RFC 2616 Section 3.6.1](http://tools.ietf.org/html/rfc2616#section-3.6.1). HTTP 1.1 implementations are **required** to support `chunked` data, per [RFC 2616 Section 4.4](http://tools.ietf.org/html/rfc2616#section-4.4), but this code does not, and it will fail if a `chunked` response is actually sent. [RFC 2616 Section 4.4](http://tools.ietf.org/html/rfc2616#section-4.4) defined the algorithm to use to read a server's response. A `readLine()` loop is definitely the wrong approach. — Remy Lebeau, Mar 28 '14 at 02:07

Why reading from a socket stream blocks forever?

1 Answers1