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https://issues.apache.org/jira/browse/HTRACE-170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14540516#comment-14540516
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Colin Patrick McCabe commented on HTRACE-170:
---------------------------------------------
Hi [~vladimirsitnikov],
I think there was a really early version of Java (maybe it was jdk4?) that did
have a non-threadsafe Random, but that is a thing of the past. The JavaDoc for
{{java.util.Random}} says:
{code}
Instances of java.util.Random are threadsafe. However, the concurrent use of
the same java.util.Random instance across threads may encounter contention and
consequent poor performance. Consider instead using ThreadLocalRandom in
multithreaded designs.
{code}
So it does work, but perhaps is slower than it might be.
It sounds like this could be improved! Would you like to create a patch
replacing these usages with a thread-local alternative?
> Non-thread safe use of Random
> -----------------------------
>
> Key: HTRACE-170
> URL: https://issues.apache.org/jira/browse/HTRACE-170
> Project: HTrace
> Issue Type: Bug
> Affects Versions: 3.3.0
> Reporter: Vladimir Sitnikov
>
> org.apache.htrace.Tracer#nonZeroRandom64 is obviously shares the same Random
> instance between multiple execution threads.
> That does not work.
> Either {{ThreadLocal<Random>}} (1.5+) or {{ThreadLocalRandom}} (1.7+) should
> be used.
> Other places with the same problem:
> org.apache.htrace.impl.CountSampler#random
> org.apache.htrace.impl.MilliSpan#nonZeroRandom64
> org.apache.htrace.impl.ProbabilitySampler#next
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