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https://issues.apache.org/jira/browse/ZOOKEEPER-2691?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16012719#comment-16012719
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ASF GitHub Bot commented on ZOOKEEPER-2691:
-------------------------------------------
Github user hanm commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/173#discussion_r116798516
--- Diff: src/java/main/org/apache/zookeeper/server/quorum/QuorumPeer.java
---
@@ -198,6 +246,12 @@ public void recreateSocketAddresses() {
public long id;
public LearnerType type = LearnerType.PARTICIPANT;
+
+ /**
+ * the time, in milliseconds, before {@link
InetAddress#isReachable} aborts
+ * in {@link #getReachableAddress}.
+ */
+ private int ipReachableTimeout = 0;
--- End diff --
I think we can remove this. This will also remove the four copies of exact
same initialization code fragment that you use to initialize the value. We can
get the sys property and parse the value inside recreateSocketAddress directly.
> recreateSocketAddresses may recreate the unreachable IP address
> ---------------------------------------------------------------
>
> Key: ZOOKEEPER-2691
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2691
> Project: ZooKeeper
> Issue Type: Bug
> Affects Versions: 3.4.8, 3.4.9, 3.4.10, 3.5.0, 3.5.1, 3.5.2, 3.4.11
> Environment: Centos6.5
> Java8
> ZooKeeper3.4.8
> Reporter: JiangJiafu
> Priority: Minor
>
> The QuorumPeer$QuorumServer.recreateSocketAddress() is used to resolved the
> hostname to a new IP address(InetAddress) when any exception happens to the
> socket. It will be very useful when a hostname can be resolved to more than
> one IP address.
> But the problem is Java API InetAddress.getByName(String hostname) will
> always return the first IP address when the hostname can be resolved to more
> than one IP address, and the first IP address may be unreachable forever. For
> example, if a machine has two network interfaces: eth0, eth1, say eth0 has
> ip1, eth1 has ip2, the relationship between hostname and the IP addresses is
> set in /etc/hosts. When I "close" the eth0 by command "ifdown eth0", the
> InetAddress.getByName(String hostname) will still return ip1, which is
> unreachable forever.
> So I think it will be better to check the IP address by
> InetAddress.isReachable(long) and choose the reachable IP address.
> I have modified the ZooKeeper source code, and test the new code in my own
> environment, and it can work very well when I turn down some network
> interfaces using "ifdown" command.
> The original code is:
> {code:title=QuorumPeer.java|borderStyle=solid}
> public void recreateSocketAddresses() {
> InetAddress address = null;
> try {
> address = InetAddress.getByName(this.hostname);
> LOG.info("Resolved hostname: {} to address: {}",
> this.hostname, address);
> this.addr = new InetSocketAddress(address, this.port);
> if (this.electionPort > 0){
> this.electionAddr = new InetSocketAddress(address,
> this.electionPort);
> }
> } catch (UnknownHostException ex) {
> LOG.warn("Failed to resolve address: {}", this.hostname, ex);
> // Have we succeeded in the past?
> if (this.addr != null) {
> // Yes, previously the lookup succeeded. Leave things as
> they are
> return;
> }
> // The hostname has never resolved. Create our
> InetSocketAddress(es) as unresolved
> this.addr = InetSocketAddress.createUnresolved(this.hostname,
> this.port);
> if (this.electionPort > 0){
> this.electionAddr =
> InetSocketAddress.createUnresolved(this.hostname,
>
> this.electionPort);
> }
> }
> }
> {code}
> After my modification:
> {code:title=QuorumPeer.java|borderStyle=solid}
> public void recreateSocketAddresses() {
> InetAddress address = null;
> try {
> address = getReachableAddress(this.hostname);
> LOG.info("Resolved hostname: {} to address: {}",
> this.hostname, address);
> this.addr = new InetSocketAddress(address, this.port);
> if (this.electionPort > 0){
> this.electionAddr = new InetSocketAddress(address,
> this.electionPort);
> }
> } catch (UnknownHostException ex) {
> LOG.warn("Failed to resolve address: {}", this.hostname, ex);
> // Have we succeeded in the past?
> if (this.addr != null) {
> // Yes, previously the lookup succeeded. Leave things as
> they are
> return;
> }
> // The hostname has never resolved. Create our
> InetSocketAddress(es) as unresolved
> this.addr = InetSocketAddress.createUnresolved(this.hostname,
> this.port);
> if (this.electionPort > 0){
> this.electionAddr =
> InetSocketAddress.createUnresolved(this.hostname,
>
> this.electionPort);
> }
> }
> }
> public InetAddress getReachableAddress(String hostname) throws
> UnknownHostException {
> InetAddress[] addresses = InetAddress.getAllByName(hostname);
> for (InetAddress a : addresses) {
> try {
> if (a.isReachable(5000)) {
> return a;
> }
> } catch (IOException e) {
> LOG.warn("IP address {} is unreachable", a);
> }
> }
> // All the IP address is unreachable, just return the first one.
> return addresses[0];
> }
> {code}
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