[Bug classpath/31010] New: select() doesn't block with DatagramChannels

[bitclash at gmail dot com]

[CLASSPATH 0.90]

The following method from class gnu.java.nio.SelectorImpl :

public abstract int select() throws IOException

doesn't follow the semantic stated by SUN's documentation:

"This method performs a blocking selection operation. It returns only after at
least one channel is selected, this selector's wakeup method is invoked, or the
current thread is interrupted, whichever comes first."

Effectively it doesn't block with a DatagramChannel associated to it. Try the
following proof-of-concept code:

import java.net.*;
import java.nio.*;
import java.nio.channels.*;

public class TestNonBlockingDatagramSocket {

    private final static String ADDR = "127.0.0.1";
    private final static int PORT = 8888;

    public static void main(String args[]) throws Exception {

        Selector selector = Selector.open();                    
        DatagramChannel channel = DatagramChannel.open();
        channel.socket().bind(new InetSocketAddress(ADDR,PORT));
        channel.configureBlocking(false);
        channel.register(selector, SelectionKey.OP_READ);

        selector.select();

        System.out.println("BUG? Select() doesn't block!");

    }
}

It blocks correctly with JDK 1.4, 1.5 and 1.6.


-- 
           Summary: select() doesn't block with DatagramChannels
           Product: classpath
           Version: 0.90
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: classpath
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bitclash at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31010