zookeeper-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-2840) Should using `System.nanoTime() ^ this.hashCode()` for StaticHostProvider
Date Mon, 16 Apr 2018 03:03:00 GMT

    [ 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--;
>         }
>     }
> ```



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)

Mime
View raw message