dev@grizzly.java.net

Re: Strange behavior of Grizzly

From: Minoru Nitta <minoru.nitta_at_jp.fujitsu.com>
Date: Mon, 08 Jun 2009 08:52:43 +0900

Hi Bongjae,


> Hi Bongjae,
>
>
> Thank you for your reply.
>
> I tested my original program
> on WindowsXP -> failed
> on Liunx -> succeeded
>
> After I applied your patch, my test program succeeded on both platforms.
> On Windows, my program failed because selector.select() returns empty set

Actually, java.nio.channels.Selector.selectedKeys().
Thanks.

> on Windows. So in some circumestances, there might be a problem.
>
>
> Minoru
>
> > Hi Minoru,
> >
> > I tested your program on Windows 2003 server.
> >
> > Your original program failed, too. But when I applied my proposed patch to your program, I could know that it worked well.
> >
> > Didn't it work well when you tested your program which was modified by my opinion on Windows XP?
> >
> > --
> > Bongjae Chang
> >
> >
> > ----- Original Message -----
> > From: "Minoru Nitta" <minoru.nitta_at_jp.fujitsu.com>
> > To: <dev_at_grizzly.dev.java.net>
> > Sent: Friday, June 05, 2009 1:01 PM
> > Subject: Re: Strange behavior of Grizzly
> >
> >
> > > Hi Bongjae, Hi all,
> > >
> > >
> > > I ran my test program on RHEL4 and it worked fine. I ran it on Windows XP,
> > > it failed. I debugged it and found out that SelectorHandler.select returned
> > > empty set at SelectorHandlerRunner.doSelect even if ready keys have been
> > > registered (So, read operation can never be executed). I think this is a
> > > bug of JDK (or somewhere else).
> > >
> > > Did you kindly test my program on Windows?
> > >
> > > Minoru
> > >
> > >> Hi Bongjae,
> > >>
> > >>
> > >> Thank you very much for your quick reply and curiosity. I understood
> > >> your proposal. Then, I would like to write my opinion.
> > >>
> > >> In UDP, it should be possible to send packets from a port where
> > >> server socket is already bound. For example, after starting my SIP server,
> > >> UDP ports status is like
> > >>
> > >> [root_at_rx200-4 ~]# netstat -a -u
> > >> Active Internet connections (servers and established)
> > >> Proto Recv-Q Send-Q Local Address Foreign Address State
> > >> udp 0 0 *:666 *:*
> > >> udp 0 0 *:669 *:*
> > >> udp 0 0 *:sunrpc *:*
> > >> udp 0 0 *:ipp *:*
> > >> udp 0 0 rx200-4:5060 *:*
> > >>
> > >> where
> > >>
> > >> udp 0 0 rx200-4:5060 *:*
> > >>
> > >> is a server socket where my SIP server is listening to from any other
> > >> addresses (*:*). Then after sending packets from the same port (i.e. 5060),
> > >> the status is like
> > >>
> > >> [root_at_rx200-4 ~]# netstat -a -u
> > >> Active Internet connections (servers and established)
> > >> Proto Recv-Q Send-Q Local Address Foreign Address State
> > >> udp 0 0 *:666 *:*
> > >> udp 0 0 *:669 *:*
> > >> udp 0 0 *:sunrpc *:*
> > >> udp 0 0 *:ipp *:*
> > >> udp 0 0 rx200-4:5060 [UNKNOWN]:6677 ESTABLISHED
> > >> udp 0 0 rx200-4:5060 *:*
> > >>
> > >> where
> > >>
> > >> udp 0 0 rx200-4:5060 [UNKNOWN]:6677 ESTABLISHED
> > >>
> > >> is a client socket which receives packets only from [UNKNOWN]:6677.
> > >>
> > >> So if packets are sent to the port 5060, the client socket is used
> > >> if the sender address is [UNKNOWN]:6677 and the server socket is used
> > >> if the sender address is not [UNKNOWN]:6677.
> > >>
> > >> I thought that the following code you mentioned in your reply makes
> > >> the
> > >>
> > >> udp 0 0 rx200-4:5060 [UNKNOWN]:6677 ESTABLISHED
> > >>
> > >> socket. But, I am not sure.
> > >>
> > >> Minoru
> > >>
> > >> > Hi Minoru,
> > >> >
> > >> > I saw your app curiously and I could reproduce your problem.
> > >> >
> > >> > When I debugged your program, I could know that your problem was perhaps caused by duplicated socket binding.
> > >> >
> > >> > I think that it is better that the client controller doesn't use a local address when it connects remote peer.
> > >> >
> > >> > See the following:
> > >> >
> > >> > In ConnectionManager.java
> > >> > ---
> > >> > private ConnectorHandler createHandlerUDP(...) {
> > >> > ...
> > >> > try {
> > >> > //connectorHandler.connect(socketRemote, local, callbackHandler);
> > >> > connectorHandler.connect(socketRemote, callbackHandler);
> > >> > } ...
> > >> > }
> > >> > ---
> > >> >
> > >> > In my opinion, the server controller's socket which was already binded with a local address could have a problem if a client tried to bind own socket with the same address locally.
> > >> >
> > >> > I could see that your program's server couldn't receive any packets though blocking DatagramSocket(UAC and UAS) sent a packet to the server controller successfully.
> > >> >
> > >> > So I thought that maybe the server had a problem.
> > >> >
> > >> > It is not certain. :-)
> > >> >
> > >> > But, I hope that my proposed patch and my words help you.
> > >> >
> > >> > Thanks!
> > >> >
> > >> > --
> > >> > Bongjae Chang
> > >> >
> > >> >
> > >> > ----- Original Message -----
> > >> > From: "Minoru Nitta" <minoru.nitta_at_jp.fujitsu.com>
> > >> > To: <dev_at_grizzly.dev.java.net>
> > >> > Sent: Tuesday, June 02, 2009 5:28 PM
> > >> > Subject: Strange behavior of Grizzly
> > >> >
> > >> >
> > >> > > Salut,
> > >> > >
> > >> > >
> > >> > >
> > >> > > I have been encountering a strange behavior of grizzly, and I need help.
> > >> > > I tested the enclosed program and it sometimes worked fine and it sometimes did
> > >> > > not work well. When it works, it repeats sending requests and responses,
> > >> > > but when it does not work well, it stops repeating.
> > >> > >
> > >> > > I have no idea where is the problem (my test program or grizzly).
> > >> > > I tested it on grizzly version 1.9.12 to 1.9.16 and the result was same.
> > >> > >
> > >> > > Thanks.
> > >> > >
> > >> > > Minoru
> > >> > >
> > >> > >
> > >> >
> > >> >
> > >> > --------------------------------------------------------------------------------
> > >> >
> > >> >
> > >> > > ---------------------------------------------------------------------
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>
>
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