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https://issues.apache.org/jira/browse/ZOOKEEPER-2447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15355703#comment-15355703
]
Edward Ribeiro commented on ZOOKEEPER-2447:
-------------------------------------------
Hi [[email protected]], my concern is not the feature itself -- it is
cool --, but the use of {{InetAddress#isReachable()}} because it seems to have
had caused some problems in the past, that is, always returning false or true
in spite of the real reachability, as seen below:
http://stackoverflow.com/questions/4779367/problem-with-isreachable-in-inetaddress-class
Of course, the SO threads that relate similar problems are usually old (five to
ten years old!), so this could not be a problem anymore, but we must
acknowledge this possible limitation. An alternative would be to roll out our
own equivalent of {{InetAddress#isReachable()}} as I scribbled below? Wdyt?
{code}
private boolean isReachable(InetAddress address, int port, int timeout) {
if (timeout < 0)
IllegalArgumentException("Timeout cannot be less than zero");
Socket socket = new Socket();
try {
socket.connect(new InetSocketAddress(address, port), timeout);
}
catch (IOException e) {
return false;
}
finally {
try {
socket.close();
} catch (IOException e) {
// Ignore any errors
}
}
return true;
}
}
{code}
> Zookeeper adds good delay when one of the quorum host is not reachable
> -----------------------------------------------------------------------
>
> Key: ZOOKEEPER-2447
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2447
> Project: ZooKeeper
> Issue Type: Bug
> Affects Versions: 3.4.6, 3.5.0
> Reporter: Vishal Khandelwal
> Assignee: Vishal Khandelwal
> Fix For: 3.5.3, 3.6.0
>
> Attachments: ZOOKEEPER-2447.3.5.patch, withfix.txt, withoutFix.txt
>
>
> StaticHostProvider --> resolveAndShuffle method adds all of the address which
> are valid in the quorum to the list, shuffles them and sends back to client
> connection class. If after shuffling if first node appear to be the one which
> is not reachable, Clientcnx.SendThread.run will keep on connecting to the
> failure till a timeout and the moves to a different node. This adds up random
> delay in zookeeper connection in case a host is down. Rather we could check
> if host is reachable in StaticHostProvider and ignore isReachable is false.
> Same as we do for UnknownHostException Exception.
> This can tested using following test code by providing a valid host which is
> not reachable. for quick test comment Collections.shuffle(tmpList,
> sourceOfRandomness); in StaticHostProvider.resolveAndShuffle
> {code}
> @Test
> public void test() throws Exception {
> EventsWatcher watcher = new EventsWatcher();
> QuorumUtil qu = new QuorumUtil(1);
> qu.startAll();
>
> ZooKeeper zk =
> new ZooKeeper("<hostnamet:2181," + qu.getConnString(), 180 * 1000,
> watcher);
>
> watcher.waitForConnected(CONNECTION_TIMEOUT * 5);
> Assert.assertTrue("connection Established", watcher.isConnected());
> zk.close();
> }
> {code}
> Following fix can be added to StaticHostProvider.resolveAndShuffle
> {code}
> if(taddr.isReachable(4000 // can be some value)) {
> tmpList.add(new InetSocketAddress(taddr,
> address.getPort()));
> }
> {code}
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