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Posted to dev@zookeeper.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2018/04/16 03:03:00 UTC
[jira] [Commented] (ZOOKEEPER-2840) Should using `System.nanoTime()
^ this.hashCode()` for StaticHostProvider
[ https://issues.apache.org/jira/browse/ZOOKEEPER-2840?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16438944#comment-16438944 ]
ASF GitHub Bot commented on ZOOKEEPER-2840:
-------------------------------------------
Github user asdf2014 commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/303#discussion_r181613274
--- Diff: src/java/main/org/apache/zookeeper/client/StaticHostProvider.java ---
@@ -71,7 +71,7 @@
* if serverAddresses is empty or resolves to an empty list
*/
public StaticHostProvider(Collection<InetSocketAddress> serverAddresses) {
- sourceOfRandomness = new Random(System.currentTimeMillis() ^ this.hashCode());
+ sourceOfRandomness = new Random(System.nanoTime() ^ this.hashCode());
--- End diff --
Hi, @maoling. Sorry for my belated comment. Indeed, i hadn't been considered this case that different clients will own different `hashcode`s. Because, in my sistuation, our Zookeeper clusters only give service to some apointed BigData components, e.g., [HBase](https://yuzhouwan.com/posts/45888/), [Druid.io](https://yuzhouwan.com/posts/5845/), [Hadoop](https://yuzhouwan.com/posts/60504/), [Kafka](https://yuzhouwan.com/posts/26002/) etc. Inside these components will have settled clients, so them can not offer too many different `hashcode`s.
> Should using `System.nanoTime() ^ this.hashCode()` for StaticHostProvider
> -------------------------------------------------------------------------
>
> Key: ZOOKEEPER-2840
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2840
> Project: ZooKeeper
> Issue Type: Bug
> Components: java client
> Affects Versions: 3.5.3
> Reporter: Benedict Jin
> Assignee: Benedict Jin
> Priority: Major
> Fix For: 3.5.4
>
> Original Estimate: 72h
> Remaining Estimate: 72h
>
> Should using `System.nanoTime() ^ this.hashCode()` for StaticHostProvider instead of `System.currentTimeMillis()`. Because if we have three Zookeeper server nodes and set the `zookeeper.leaderServes` as `no`, then those connections from client will always connect with the first Zookeeper server node. Due to...
> ```java
> @Test
> public void testShuffle() throws Exception {
> LinkedList<InetSocketAddress> inetSocketAddressesList = new LinkedList<>();
> inetSocketAddressesList.add(new InetSocketAddress(0));
> inetSocketAddressesList.add(new InetSocketAddress(1));
> inetSocketAddressesList.add(new InetSocketAddress(2));
> /*
> 1442045361
> currentTime: 1499253530044, currentTime ^ hashCode: 1500143845389, Result: 1 2 0
> currentTime: 1499253530044, currentTime ^ hashCode: 1500143845389, Result: 2 0 1
> currentTime: 1499253530045, currentTime ^ hashCode: 1500143845388, Result: 0 1 2
> currentTime: 1499253530045, currentTime ^ hashCode: 1500143845388, Result: 1 2 0
> currentTime: 1499253530046, currentTime ^ hashCode: 1500143845391, Result: 1 2 0
> currentTime: 1499253530046, currentTime ^ hashCode: 1500143845391, Result: 1 2 0
> currentTime: 1499253530046, currentTime ^ hashCode: 1500143845391, Result: 1 2 0
> currentTime: 1499253530046, currentTime ^ hashCode: 1500143845391, Result: 1 2 0
> currentTime: 1499253530047, currentTime ^ hashCode: 1500143845390, Result: 1 2 0
> currentTime: 1499253530047, currentTime ^ hashCode: 1500143845390, Result: 1 2 0
> */
> internalShuffleMillis(inetSocketAddressesList);
> /*
> 146611050
> currentTime: 22618159623770, currentTime ^ hashCode: 22618302559536, Result: 2 1 0
> currentTime: 22618159800738, currentTime ^ hashCode: 22618302085832, Result: 0 1 2
> currentTime: 22618159967442, currentTime ^ hashCode: 22618302248888, Result: 1 0 2
> currentTime: 22618160135080, currentTime ^ hashCode: 22618302013634, Result: 2 1 0
> currentTime: 22618160302095, currentTime ^ hashCode: 22618301535077, Result: 2 1 0
> currentTime: 22618160490260, currentTime ^ hashCode: 22618301725822, Result: 1 0 2
> currentTime: 22618161566373, currentTime ^ hashCode: 22618300303823, Result: 1 0 2
> currentTime: 22618161745518, currentTime ^ hashCode: 22618300355844, Result: 2 1 0
> currentTime: 22618161910357, currentTime ^ hashCode: 22618291603775, Result: 2 1 0
> currentTime: 22618162079549, currentTime ^ hashCode: 22618291387479, Result: 0 1 2
> */
> internalShuffleNano(inetSocketAddressesList);
> inetSocketAddressesList.clear();
> inetSocketAddressesList.add(new InetSocketAddress(0));
> inetSocketAddressesList.add(new InetSocketAddress(1));
> /*
> 415138788
> currentTime: 1499253530050, currentTime ^ hashCode: 1499124456998, Result: 0 1
> currentTime: 1499253530050, currentTime ^ hashCode: 1499124456998, Result: 0 1
> currentTime: 1499253530050, currentTime ^ hashCode: 1499124456998, Result: 0 1
> currentTime: 1499253530050, currentTime ^ hashCode: 1499124456998, Result: 0 1
> currentTime: 1499253530050, currentTime ^ hashCode: 1499124456998, Result: 0 1
> currentTime: 1499253530050, currentTime ^ hashCode: 1499124456998, Result: 0 1
> currentTime: 1499253530053, currentTime ^ hashCode: 1499124456993, Result: 0 1
> currentTime: 1499253530055, currentTime ^ hashCode: 1499124456995, Result: 0 1
> currentTime: 1499253530055, currentTime ^ hashCode: 1499124456995, Result: 0 1
> currentTime: 1499253530055, currentTime ^ hashCode: 1499124456995, Result: 0 1
> */
> internalShuffleMillis(inetSocketAddressesList);
> /*
> 13326370
> currentTime: 22618168292396, currentTime ^ hashCode: 22618156149774, Result: 1 0
> currentTime: 22618168416181, currentTime ^ hashCode: 22618156535703, Result: 1 0
> currentTime: 22618168534056, currentTime ^ hashCode: 22618156432394, Result: 0 1
> currentTime: 22618168666548, currentTime ^ hashCode: 22618155774358, Result: 0 1
> currentTime: 22618168818946, currentTime ^ hashCode: 22618155623712, Result: 0 1
> currentTime: 22618168936821, currentTime ^ hashCode: 22618156011863, Result: 1 0
> currentTime: 22618169056251, currentTime ^ hashCode: 22618155893721, Result: 1 0
> currentTime: 22618169611103, currentTime ^ hashCode: 22618157370237, Result: 1 0
> currentTime: 22618169744528, currentTime ^ hashCode: 22618156713138, Result: 1 0
> currentTime: 22618171273170, currentTime ^ hashCode: 22618184562672, Result: 1 0
> */
> internalShuffleNano(inetSocketAddressesList);
> }
> private void internalShuffleMillis(LinkedList<InetSocketAddress> inetSocketAddressesList) throws Exception {
> int hashCode = new StaticHostProvider(inetSocketAddressesList).hashCode();
> System.out.println(hashCode);
> int count = 10;
> Random r;
> while (count > 0) {
> long currentTime = System.currentTimeMillis();
> r = new Random(currentTime ^ hashCode);
> System.out.print(String.format("currentTime: %s, currentTime ^ hashCode: %s, Result: ",
> currentTime, currentTime ^ hashCode));
> Collections.shuffle(inetSocketAddressesList, r);
> for (InetSocketAddress inetSocketAddress : inetSocketAddressesList) {
> System.out.print(String.format("%s ", inetSocketAddress.getPort()));
> }
> System.out.println();
> count--;
> }
> }
> private void internalShuffleNano(LinkedList<InetSocketAddress> inetSocketAddressesList) throws Exception {
> int hashCode = new StaticHostProvider(inetSocketAddressesList).hashCode();
> System.out.println(hashCode);
> int count = 10;
> Random r;
> while (count > 0) {
> long currentTime = System.nanoTime();
> r = new Random(currentTime ^ hashCode);
> System.out.print(String.format("currentTime: %s, currentTime ^ hashCode: %s, Result: ",
> currentTime, currentTime ^ hashCode));
> Collections.shuffle(inetSocketAddressesList, r);
> for (InetSocketAddress inetSocketAddress : inetSocketAddressesList) {
> System.out.print(String.format("%s ", inetSocketAddress.getPort()));
> }
> System.out.println();
> count--;
> }
> }
> ```
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