[ https://issues.apache.org/jira/browse/SPARK21401?page=com.atlassian.jira.plugin.system.issuetabpanels:alltabpanel
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Peng Meng updated SPARK21401:

Description:
The most of BoundedPriorityQueue usages in ML/MLLIB are:
Get the value of BoundedPriorityQueue, then sort it.
For example, in Word2Vec: pq.toSeq.sortBy(_._2)
in ALS, pq.toArray.sorted()
The test results show using pq.poll() is much faster than sort the value.
For example, in PR https://github.com/apache/spark/pull/18624
We get the sorted value of pq by the following code:
{quote}
var size = pq.size
while(size > 0) {
size = 1
val factor = pq.poll
}{quote}
If using the generally used methods: pq.toArray.sorted() to get the sorted value of pq. There
is about 10% performance reduction.
It is good to add the poll function for BoundedPriorityQueue, since many usages of PQ need
the sorted value.
was:
The most of BoundedPriorityQueue usages in ML/MLLIB are:
Get the value of BoundedPriorityQueue, then sort it.
For example, in Word2Vec: pq.toSeq.sortBy(_._2)
in ALS, pq.toArray.sorted()
The test results show using pq.poll() is much faster than sort the value.
For example, in PR https://github.com/apache/spark/pull/18624
We get the sorted value of pq by the following code:
{quote}
var size = pq.size
while(size > 0) {
size = 1
val factor = pq.poll
}{quote}
If using the generally used methods: pq.toArray.sorted() to get the sorted value of pq. There
is about 10% performance reduction.
It is good to add the poll function for BoundedPriorityQueue, since many usages of PQ need
the sorted value.
> add poll function for BoundedPriorityQueue
> 
>
> Key: SPARK21401
> URL: https://issues.apache.org/jira/browse/SPARK21401
> Project: Spark
> Issue Type: Improvement
> Components: ML, MLlib
> Affects Versions: 2.3.0
> Reporter: Peng Meng
> Priority: Minor
>
> The most of BoundedPriorityQueue usages in ML/MLLIB are:
> Get the value of BoundedPriorityQueue, then sort it.
> For example, in Word2Vec: pq.toSeq.sortBy(_._2)
> in ALS, pq.toArray.sorted()
> The test results show using pq.poll() is much faster than sort the value.
> For example, in PR https://github.com/apache/spark/pull/18624
> We get the sorted value of pq by the following code:
> {quote}
> var size = pq.size
> while(size > 0) {
> size = 1
> val factor = pq.poll
> }{quote}
> If using the generally used methods: pq.toArray.sorted() to get the sorted value of pq.
There is about 10% performance reduction.
> It is good to add the poll function for BoundedPriorityQueue, since many usages of PQ
need the sorted value.

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