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https://issues.apache.org/jira/browse/MATH-899?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13499680#comment-13499680
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Thomas Neidhart commented on MATH-899:
--------------------------------------
{quote}
But I have a hard time implementing a unit test that would consistently
reproduce the error reported here: It does not necessarily happen even with a
fairly large number of threads.
{quote}
hmm, I am not sure if this is necessary or achievable. When looking at
comparable things (e.g. commons-collections, or openjdk), there also do not
exist specific tests to prove that the synchronization prevents a race
condition in not thread-safe code.
I think in this case it would be sufficient to do a proof by induction (sort
of):
* we know that e.g. MersenneTwister is not thread-safe
* by providing a fully synchronized wrapper we make it thread-safe
btw. in the test you refer to MATH-900 while its actually MATH-899.
> A random crash of MersenneTwister random generator
> --------------------------------------------------
>
> Key: MATH-899
> URL: https://issues.apache.org/jira/browse/MATH-899
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.0
> Environment: Windows 7, JDK 1.7.05
> Reporter: Alexander Nozik
> Priority: Minor
> Attachments: SynchronizedRandomGenerator.java,
> SynchronizedRandomGeneratorTest.java
>
>
> There is a very small probability that MersenneTwister generator gives a
> following error:
> java.lang.ArrayIndexOutOfBoundsException: 624
> in MersenneTwister.java line 253
> The error is completely random and its probability is about 1e-8.
> UPD: The problem most probably arises only in multy-thread mode.
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