Re: RFR: JDK-8057556: JDP should better handle non-active interfaces

[Yasumasa Suenaga]

Hi Jaroslav,

I could not receive your email.
So I reply from another email.

L103 Please, move "else" to the previous line

I will fix it.

L96-100 Do we still need these lines? Isn't
`channel.setOption(StandardSocketOptions.IP_MULTICAST_IF, interf);`
enough to listen on the interface?

I think we should remove bind() call.
If we run multiple VM with same com.sun.management.jdp.source_addr value
and on same OS, we may encounter BindException in current implementation
as following:

----------
Error: Exception thrown by the agent : java.rmi.server.ExportException: Port 
already in use: 7091; nested exception is:
        java.net.BindException: Address already in use
----------

If it should be treated as another issue, I will file it to JBS and
create a new patch.

I will upload new webrev for JDK-8057556 after this discussion.


Thanks,

Yasumasa


(2014/09/05 19:28), Yasumasa Suenaga wrote:

Hi Peter,

I fixed it and created new webrev.
http://cr.openjdk.java.net/~ysuenaga/JDK-8057556/webrev.1/

Could you review it again?


Thanks,

Yasumasa


(2014/09/05 17:20), Peter Allwin wrote:

Looks like only the first Interface will be considered if no srcAddress is 
provided (succeeded will be false and we will throw to exit the while loop). Is 
this intended?

Thanks!
/peter

On 4 sep 2014, at 17:59, Yasumasa Suenaga <yasue...@gmail.com> wrote:

Hi all,

Thank you so much, Dmitry!

I've created webrev for it.
http://cr.openjdk.java.net/~ysuenaga/JDK-8057556/webrev.0/

Please review.


Thanks,

Yasumasa


(2014/09/04 21:26), Dmitry Samersoff wrote:

Yasumasa,

The CR number is JDK-8057556

I'll care about it's integration.

-Dmitry

On 2014-09-02 18:52, Yasumasa Suenaga wrote:
Hi all,

I'm trying to use JDP on my Fedora20 machine.
My machine has two NICs and only one NIC is up.

I passed system properties as below, however JDP broadcaster
thread was not started:

   -Dcom.sun.management.jmxremote.port=7091
   -Dcom.sun.management.jmxremote.authenticate=false
   -Dcom.sun.management.jmxremote.ssl=false
   -Dcom.sun.management.jmxremote.autodiscovery=true
   -Dcom.sun.management.jdp.name=TEST

I checked exceptions with jdb, SocketException was occurred in
JDPControllerRunner#run(), and it was caused by another NIC
is down.

Currently, DiagramChannel which is used in JDPBroadcaster
tries to send JDP packet through all "UP" NICs.
However, NIC which is controlled by NetworkManager seems to
be still "UP" when ifdown command is executed.
(It seems to be removed IP address from NIC only.)


This problem may be Fedora, however I think it should be
improved in JDK.
I've created a patch as below, and it works fine in my environment.
(jdk9/dev/jdk)

If this patch may be accepted, I will file this to JBS.

--------------------
diff -r 68a6bb51cb26 
src/java.management/share/classes/sun/management/jdp/JdpBroadcaster.java
--- a/src/java.management/share/classes/sun/management/jdp/JdpBroadcaster.java  
  Mon Sep 01 13:33:28 2014 +0200
+++ b/src/java.management/share/classes/sun/management/jdp/JdpBroadcaster.java  
  Tue Sep 02 23:25:50 2014 +0900
@@ -35,6 +35,7 @@
  import java.nio.ByteBuffer;
  import java.nio.channels.DatagramChannel;
  import java.nio.channels.UnsupportedAddressTypeException;
+import java.util.Enumeration;

  /**
   * JdpBroadcaster is responsible for sending pre-built JDP packet across a Net
@@ -79,6 +80,15 @@
          if (srcAddress != null) {
              // User requests particular interface to bind to
              NetworkInterface interf = 
NetworkInterface.getByInetAddress(srcAddress);
+
+            if (interf == null) {
+                throw new JdpException("Unable to get network interface for " 
+ srcAddress.toString());
+            }
+
+            if (!interf.isUp() || !interf.supportsMulticast()) {
+                throw new JdpException(interf.getName() + " does not support 
multicast.");
+            }
+
              try {
                  channel.bind(new InetSocketAddress(srcAddress, 0));
              } catch (UnsupportedAddressTypeException ex) {
@@ -86,6 +96,23 @@
              }
              channel.setOption(StandardSocketOptions.IP_MULTICAST_IF, interf);
          }
+        else {
+            Enumeration<NetworkInterface> nics = 
NetworkInterface.getNetworkInterfaces();
+            while (nics.hasMoreElements()) {
+                NetworkInterface nic = nics.nextElement();
+
+                if (nic.isUp() && nic.supportsMulticast()) {
+                    try {
+                        
channel.setOption(StandardSocketOptions.IP_MULTICAST_IF, nic);
+                    } catch (IOException ex) {
+                        System.err.println("WARNING: JDP broadcaster cannot use " + 
nic.getName() + ": " + ex.getMessage());
+                    }
+                }
+
+            }
+
+        }
+
      }

      /**
--------------------


Thanks,

Yasumasa