I filed a bug report on this before, but now I can't find it, so I'm refiling. I did get
a note from the bugtraq folks that one of my bug reports got corrupted, so perhaps
it was this one. I'm filing this as java/runtime because there is a definite problem
in the Green-threads code when a close happens during a read of the same
file descriptor, but java.net.PlainSocketImpl also contributes (see my evaluation.)
And now to the bug....

I wrote a simple TCP proxy server using sun.net.NetworkClient and
sun.net.NetworkServer. After I thought I had all the bugs out I still had every
other connection get dropped immediately. Here's a modified version of the
code that demonstrates the problem. It also includes a work-around.

import sun.net.NetworkClient;
import sun.net.NetworkServer;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
 
class ReaderThread extends Thread {
 
    ReaderThread(InputStream i, OutputStream o) {
        input = i;
        output = o;
    }
 
    public void run() {
        byte buf[] = new byte[2048];
        try {
            int n;
            while ((n = input.read(buf, 0, buf.length)) > 0) {
                output.write(buf, 0, n);
                output.flush();
            }
        } catch (IOException e) {
        }
    }
    private InputStream input;
    private OutputStream output;
}
 
class ProxyClient extends NetworkClient {
    public ProxyClient(String host, int port) throws IOException {
        super(host, port);
    }
    public String toString() {
        return serverSocket.toString();
    }
}
 
class ProxyServer extends NetworkServer {
    ProxyServer(String server, int port) {
        proxyServer = server;
        proxyPort = port;
        workAround = false;
    }
    public void serviceRequest() throws IOException {
        try {
            ProxyClient client = new ProxyClient(proxyServer, proxyPort);
            Thread t = new ReaderThread(clientInput, client.serverOutput);
            t.start();
            writeSide(client);
            // For bug to show up, ReaderThread must be in read()
            Thread.sleep(5);
            client.closeServer();
            if (workAround) {
                // Work-around bug
                clientSocket.close();
                t.join();
            }
        } catch (Exception e) {
            System.err.println("serviceRequest " + e);
        }
    }
    private void writeSide(NetworkClient client) throws IOException {
        byte buf[] = new byte[2048];
        int n;
        while ((n = client.serverInput.read(buf, 0, buf.length)) >= 0) {
            clientOutput.write(buf, 0, n);
            clientOutput.flush();
        }
    }
    public void tryWorkAround(boolean maybe) {
System.out.println("tryWorkAround " + maybe);
        workAround = maybe;
    }
 
    private String proxyServer;
    private int proxyPort;
    private boolean workAround;
}
 
class Proxy {
    public static void main(String args[]) throws IOException {
        String httpServer = args[0];
        int httpPort = Integer.parseInt(args[1]);
        int localPort = Integer.parseInt(args[2]);
        ProxyServer p = new ProxyServer(httpServer, httpPort);
        p.startServer(localPort);
        for (int i = 0; i < 8; ++i) {
            p.tryWorkAround((i / 4) % 2 == 1);
            echoTest(localPort);
        }
        System.exit(0);
    }
 
    static void echoTest(int port) throws IOException {
        NetworkClient client = new NetworkClient("localhost", port);
        byte buf[] = new byte[128];
        client.serverOutput.println("GET foo");
        System.gc();
        System.runFinalization();
        System.gc();
        System.runFinalization();
        int n;
        while ((n = client.serverInput.read(buf, 0, buf.length)) > 0) {
        }
    }
}

% /usr/local/java/latest/bin/javac ProxyServer.java
% /usr/local/java/latest/bin/java Proxy webcache 8080 7771
tryWorkAround false
tryWorkAround false
java.io.IOException: Resource temporarily unavailable
        at java.net.SocketInputStream.read(SocketInputStream.java:89)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java)
        at java.io.BufferedInputStream.read(BufferedInputStream.java)
        at Proxy.echoTest(ProxyServer.java:103)
        at Proxy.main(ProxyServer.java:89)

% /usr/local/java/latest/bin/java_g Proxy webcache 8080 7771
tryWorkAround false
tryWorkAround false
tryWorkAround false
tryWorkAround false
tryWorkAround true
java.io.IOException: Bad file number
        at java.net.SocketInputStream.read(SocketInputStream.java:89)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java)
        at java.io.BufferedInputStream.read(BufferedInputStream.java)
        at Proxy.echoTest(ProxyServer.java:103)
        at Proxy.main(ProxyServer.java:89)

[ Now I change the expression for tryWorkAround from (i / 4) % 2 == 1 to
  (i / 4) % 2 == 0 so we go true, true, true, true, false, false, false, false ... ]

springbok /tmp [130] % /usr/local/java/latest/bin/java Proxy webcache 8080 7771 tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround false
tryWorkAround false
tryWorkAround false
tryWorkAround false
serviceRequest java.io.IOException: Resource temporarily unavailable
springbok /tmp [131] % /usr/local/java/latest/bin/java Proxy webcache 8080 7771
tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround false
tryWorkAround false
tryWorkAround false
java.io.IOException: Resource temporarily unavailable
        at java.net.SocketInputStream.read(SocketInputStream.java:89)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java)
        at java.io.BufferedInputStream.read(BufferedInputStream.java)
        at Proxy.echoTest(ProxyServer.java:103)
        at Proxy.main(ProxyServer.java:89)
^C
springbok /tmp [132] % /usr/local/java/latest/bin/java Proxy webcache 8080 7771
tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround false
tryWorkAround false
tryWorkAround false
tryWorkAround false
serviceRequest java.net.SocketException: Bad file number

springbok /tmp [133] % /usr/local/java/latest/bin/java_g Proxy webcache 8080 7771
tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround false
tryWorkAround false
tryWorkAround false
tryWorkAround false
java.io.IOException: Bad file number
        at java.net.SocketInputStream.read(SocketInputStream.java:89)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java)
        at java.io.BufferedInputStream.read(BufferedInputStream.java)
        at Proxy.echoTest(ProxyServer.java:103)
        at Proxy.main(ProxyServer.java:89)
^C
springbok /tmp [134] % /usr/local/java/latest/bin/java_g Proxy webcache 8080 7771
tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround true
tryWorkAround false
tryWorkAround false
tryWorkAround false
tryWorkAround false
java.io.IOException: Resource temporarily unavailable
        at java.net.SocketInputStream.read(SocketInputStream.java:89)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java)
        at java.io.BufferedInputStream.read(BufferedInputStream.java)
        at Proxy.echoTest(ProxyServer.java:103)
        at Proxy.main(ProxyServer.java:89)
^C

DREL 8/23/96