Github user eribeiro commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/173#discussion_r101845264
--- Diff: src/java/main/org/apache/zookeeper/server/quorum/QuorumPeer.java
---
@@ -181,6 +197,33 @@ public void recreateSocketAddresses() {
}
}
+ /**
+ * Resolve the hostname to IP addresses, and find one reachable
address.
+ *
+ * @param hostname the name of the host
+ * @param timeout the time, in millseconds, before {@link
InetAddress#isReachable}
+ * aborts
+ * @return a reachable IP address. If no such IP address can be
found,
+ * just return the first IP address of the hostname.
+ *
+ * @exception UnknownHostException
+ */
+ public InetAddress getReachableAddress(String hostname, int
timeout)
+ throws UnknownHostException {
+ InetAddress[] addresses = InetAddress.getAllByName(hostname);
+ for (InetAddress a : addresses) {
+ try {
+ if (a.isReachable(timeout)) {
--- End diff --
My main problem with this PR is that call to `isReachable(timeout)` for two
reasons:
1) the most important one: `isReachable(timeout)` seems unreliable so there
are plenty cases where it returns false even tough the node is reachable or
vice-versa! https://bugs.openjdk.java.net/browse/JDK-8159410 (google
"InetAddress.isReachable not working" or "InetAddress.isReachable unreliable"
to see further cases).
2) This timeout can add an arbitrary delay until a reachable node can be
tested.
IDK what a good compromise would be for both points above (leaving as it is
today could work, so no problem, even tough I am a bit concerned), but maybe we
could use a solution similar to ZOOKEEPER-2184 and return the next address in
the array (using `next = ++next % addresses.length` to prevent out of bound
exceptions).
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