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https://issues.apache.org/jira/browse/SPARK-17306?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15449512#comment-15449512
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Tim Hunter commented on SPARK-17306:
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[~srowen] yes I had a discussion yesterday with [~clockfly]. The issue is
performance, not correctness, by the way. The fix is to add a call to the
compression: the compression threshold should be
used in insert() after inserting the head buffer at this line:
https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/QuantileSummaries.scala#L66
Unless someone else wants to step in, I will be happy to fix this issue.
> Memory leak in QuantileSummaries
> --------------------------------
>
> Key: SPARK-17306
> URL: https://issues.apache.org/jira/browse/SPARK-17306
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Reporter: Sean Zhong
>
> compressThreshold was not referenced anywhere
> {code}
> class QuantileSummaries(
> val compressThreshold: Int,
> val relativeError: Double,
> val sampled: ArrayBuffer[Stats] = ArrayBuffer.empty,
> private[stat] var count: Long = 0L,
> val headSampled: ArrayBuffer[Double] = ArrayBuffer.empty) extends
> Serializable
> {code}
> And, it causes memory leak, QuantileSummaries takes unbounded memory
> {code}
> val summary = new QuantileSummaries(10000, relativeError = 0.001)
> // Results in creating an array of size 100000000 !!!
> (1 to 100000000).foreach(summary.insert(_))
> {code}
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