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From "Edward Ribeiro (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-1990) suspicious instantiation of java Random instances
Date Sat, 24 Mar 2018 15:18:00 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16412656#comment-16412656
] 

Edward Ribeiro commented on ZOOKEEPER-1990:
-------------------------------------------

As you are tackling this issue, it would be nice to evaluate the use of ThreadLocalRandom
( [https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ThreadLocalRandom.html] )
instead of Random, if possible. It's been available since JDK7 and offers less contention
and overhead.

> suspicious instantiation of java Random instances
> -------------------------------------------------
>
>                 Key: ZOOKEEPER-1990
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1990
>             Project: ZooKeeper
>          Issue Type: Bug
>    Affects Versions: 3.5.0
>            Reporter: Patrick Hunt
>            Assignee: Mark Fenes
>            Priority: Critical
>             Fix For: 3.5.4, 3.6.0
>
>
> It's not clear to me why we are doing this, but it looks very suspicious. Why aren't
we just calling "new Random()" in these cases? (even for the tests I don't really see it -
typically that would just be for repeatability)
> {noformat}
> ag "new Random[ \t]*\(" .
> src/java/main/org/apache/zookeeper/ClientCnxn.java
> 817:        private Random r = new Random(System.nanoTime());        
> src/java/main/org/apache/zookeeper/client/StaticHostProvider.java
> 75:       sourceOfRandomness = new Random(System.currentTimeMillis() ^ this.hashCode());
> 98:        sourceOfRandomness = new Random(randomnessSeed);
> src/java/main/org/apache/zookeeper/server/quorum/AuthFastLeaderElection.java
> 420:                rand = new Random(java.lang.Thread.currentThread().getId()
> src/java/main/org/apache/zookeeper/server/SyncRequestProcessor.java
> 64:    private final Random r = new Random(System.nanoTime());
> src/java/main/org/apache/zookeeper/server/ZooKeeperServer.java
> 537:        Random r = new Random(id ^ superSecret);
> 554:        Random r = new Random(sessionId ^ superSecret);
> src/java/test/org/apache/zookeeper/server/quorum/WatchLeakTest.java
> 271:        Random r = new Random(SESSION_ID ^ superSecret);
> src/java/test/org/apache/zookeeper/server/quorum/CommitProcessorTest.java
> 151:            Random rand = new Random(Thread.currentThread().getId());
> 258:            Random rand = new Random(Thread.currentThread().getId());
> 288:        Random rand = new Random(Thread.currentThread().getId());
> src/java/test/org/apache/zookeeper/test/StaticHostProviderTest.java
> 40:    private Random r = new Random(1);
> {noformat}



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