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https://issues.apache.org/jira/browse/STATISTICS-99?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alex Herbert resolved STATISTICS-99.
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Fix Version/s: 1.4
Assignee: Alex Herbert
Resolution: Fixed
Limit byte allocation to 512 MiB in commit:
325a9b044cb9e0998aabd3cf81e999998cfeeb85
> The MannWhitneyUTest can allocate very large memory to compute the exact
> p-value
> --------------------------------------------------------------------------------
>
> Key: STATISTICS-99
> URL: https://issues.apache.org/jira/browse/STATISTICS-99
> Project: Commons Statistics
> Issue Type: Bug
> Components: inference
> Affects Versions: 1.3
> Reporter: Alex Herbert
> Assignee: Alex Herbert
> Priority: Minor
> Fix For: 1.4
>
>
> The MannWhitneyUTest can compute an exact p-value using a method that
> requires tabulation of double values. The default limit for the AUTO
> configuration will consume a maximum of approximately 2.86MiB of memory
> before switching to the asymptotic approximation when max(n, m) >= 50.
> A user can configure the test to use the exact p-value computation for any
> size (n, m). The binomial coefficient value binom(n + m, m) limits the size
> that can be used to compute the p-value. The largest value of n+m for which
> all coefficients can fit into a double is 1029. Larger n+m may result in
> infinity depending on the value of m. Any min(m, n) >= 515 is infinite and
> will not call the exact computation.
> For a m=n=514 the computation is possible and the maximum memory is
> approximately 32.6 GiB.
> A suggested fix it to have a default value for the maximum space to allocate
> for the exact p-value computation. The test suite uses allocations up to
> 389MiB or 5.1e7 doubles. A limit of 512MiB allows reasonable usage of the
> exact p-value computation but will require a user to opt in to large
> allocations.
> Issue identified using a security scan.
>
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