I'm trying to code a server-client communicating application which uses two separate threads, one for input and one for output. I'm having a weird "deadlock" issue, though: when one thread reads input, but the client hasn't sent anything, the thread stops (since it's waiting for input). However, for some reason, while the input thread is blocked, the output thread can't write anything.
This is illustrated in this code sample:
import java.io.*;
import java.net.*;
import java.nio.*;
import java.nio.channels.*;
public class TestServer {
public static void main(String... args) throws IOException {
/* Creates a server socket that lurks about our port waiting for connections */
ServerSocketChannel serverChannel = ServerSocketChannel.open();
serverChannel.configureBlocking(false);
serverChannel.socket().bind(new InetSocketAddress(4114));
while(true){
SocketChannel connectionChannel = serverChannel.accept();
if(connectionChannel != null){
final Socket connection = connectionChannel.socket();
new Thread(){
public void run(){
try {
System.out.println("READING");
System.out.flush();
// If the next line is commented out, nothing blocks
connection.getInputStream().read();
System.out.println("DONE READING");
System.out.flush();
} catch (Exception e){
e.printStackTrace();
}
}
}.start();
new Thread(){
public void run(){
try {
System.out.println("WRITING");
System.out.flush();
new DataOutputStream(connection.getOutputStream()).writeBytes("AUGH!!!");
//connection.getOutputStream().write(5);
System.out.println("DONE WRITING");
System.out.flush();
} catch (Exception e){
e.printStackTrace();
}
}
}.start();
break;
}
}
}
}
And the client code:
import java.net.*;
import java.io.*;
public class TestClient {
public static void main(String... args) throws IOException {
Socket connection = new Socket("127.0.0.1", 4114);
while(true){
System.out.println(connection.getInputStream().read());
}
}
}
The code sample above blocks, but if the line in the server is commented out it doesn't. Why is that? Is a socket limited to only waiting for input/output at the same time? What's going on?
