[jboss-jira] [JBoss JIRA] (JGRP-2257) UDP#PacketReceiver stuck in busy loop when socket throws closed exception but socket is not closed

[Paul Illingworth (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-2257?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13574196#comment-13574196 ] 

Paul Illingworth commented on JGRP-2257:
----------------------------------------

I don't think it is fixable either. Well, it would be possible to query the SocketException message to see if it is "socket closed" but this is always going to be fragile and given that it appears that this is a problem that has been seen before probably not worth doing.

I raised the ticket to more to record what was observed in case it is ever seen again.

I am more than happy for this to be closed.

> UDP#PacketReceiver stuck in busy loop when socket throws closed exception but socket is not closed
> --------------------------------------------------------------------------------------------------
>
>                 Key: JGRP-2257
>                 URL: https://issues.jboss.org/browse/JGRP-2257
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 3.6.12
>         Environment: Windows Server 2016, 32GBytes memory running as a Hyper-V guest
> java version "1.8.0_131"
> Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
> Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)
> It was reported with just a single node running.
>            Reporter: Paul Illingworth
>            Assignee: Bela Ban
>             Fix For: 4.0.12
>
>
> I have a had a report of a scenario where it looks like the UDP#PacketReceiver is stuck spinning in a busy loop. The following is a snippet of the log file from the system in question. 
> {noformat}
> 2018-03-16 14:05:43,273 SEVERE [] (214,unicast receiver,shared=udp) JGRP000190: failed receiving packet
> java.net.SocketException: socket closed
>               at java.net.TwoStacksPlainDatagramSocketImpl.peekData(Native Method)
>               at java.net.DatagramSocket.receive(DatagramSocket.java:743)
>               at org.jgroups.protocols.UDP$PacketReceiver.run(UDP.java:694)
>               at java.lang.Thread.run(Thread.java:748)
>  
> 2018-03-16 14:05:43,273 SEVERE [] (214,unicast receiver,shared=udp) JGRP000190: failed receiving packet
> java.net.SocketException: socket closed
>               at java.net.TwoStacksPlainDatagramSocketImpl.peekData(Native Method)
>               at java.net.DatagramSocket.receive(DatagramSocket.java:743)
>               at org.jgroups.protocols.UDP$PacketReceiver.run(UDP.java:694)
>               at java.lang.Thread.run(Thread.java:748)
>  
> 2018-03-16 14:05:43,273 SEVERE [] (214,unicast receiver,shared=udp) JGRP000190: failed receiving packet
> java.net.SocketException: socket closed
>               at java.net.TwoStacksPlainDatagramSocketImpl.peekData(Native Method)
>               at java.net.DatagramSocket.receive(DatagramSocket.java:743)
>               at org.jgroups.protocols.UDP$PacketReceiver.run(UDP.java:694)
>               at java.lang.Thread.run(Thread.java:748)
>  {noformat}
> Looking at the code it looks like the call to receive a packet 
> {code:java}
> receiver_socket.receive(packet);
> {code}
> results in an exception being thrown because the socket is closed but then when the exception is caught 
> {code:java}
> if(receiver_socket.isClosed()) {
> {code}
> method is queried which says the socket has not been closed and the loop then continues for ever.
> I guess this is related to JGRP-1669. To quote
> _I hope there is no condition which causes the socket receive() to spit out endless exceptions while not being closed..._



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