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https://issues.apache.org/jira/browse/FLINK-2533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14736038#comment-14736038
]
ASF GitHub Bot commented on FLINK-2533:
---------------------------------------
Github user ChengXiangLi commented on a diff in the pull request:
https://github.com/apache/flink/pull/1110#discussion_r39002786
--- Diff:
flink-java/src/main/java/org/apache/flink/api/java/sampling/PoissonSampler.java
---
@@ -28,11 +29,16 @@
*
* @param <T> The type of sample.
* @see <a
href="https://en.wikipedia.org/wiki/Poisson_distribution";>https://en.wikipedia.org/wiki/Poisson_distribution</a>
+ * @see <a
href="http://erikerlandson.github.io/blog/2014/09/11/faster-random-samples-with-gap-sampling/";>Gap
Sampling</a>
*/
public class PoissonSampler<T> extends RandomSampler<T> {
private PoissonDistribution poissonDistribution;
private final double fraction;
+ private final Random random = new Random();
--- End diff --
The "random" instance should better to be initialized in constructor method
and use the seed parameter while available.
> Gap based random sample optimization
> ------------------------------------
>
> Key: FLINK-2533
> URL: https://issues.apache.org/jira/browse/FLINK-2533
> Project: Flink
> Issue Type: Improvement
> Components: Core
> Reporter: Chengxiang Li
> Priority: Minor
>
> For random sampler with fraction, like BernoulliSampler and PoissonSampler,
> Gap based random sampler could exploit O(k) sample implementation instead of
> previous O\(n\) sample implementation, it should perform better while sample
> fraction is very small. [This
> blog|http://erikerlandson.github.io/blog/2014/09/11/faster-random-samples-with-gap-sampling/]
> describes more detail about gap based random sampler.
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