[SPARK-34189][ML] w2v findSynonyms optimization

[zhengruifeng]

What changes were proposed in this pull request?

1, use Guavaording instead of BoundedPriorityQueue;
2, use local variables;
3, avoid conversion: ml.vector -> mllib.vector

Why are the changes needed?

this pr is about 30% faster than existing impl

Does this PR introduce any user-facing change?

NO

How was this patch tested?

existing testsuites

[zhengruifeng]

train a model with https://en.wikipedia.org/wiki/Word2vec as the training data;

import org.apache.spark.ml.feature._

val df = spark.read.text("/d0/Dev/PRs/Word2vec")
val df2 = df.as[String].map(_.split(" ")).toDF("words")

val w2v = new Word2Vec().setInputCol("words").setMaxIter(1)
val w2vm = w2v.fit(df2)
w2vm.save("/tmp/w2vm")

performance test

import org.apache.spark.ml.feature._

val w2vm = Word2VecModel.load("/tmp/w2vm")
val words = w2vm.getVectors.select("word").as[String].collect

val start = System.currentTimeMillis; Seq.range(0, 10000).foreach { i => words.foreach(word => w2vm.findSynonymsArray(word, 10)) }; val end = System.currentTimeMillis; val duration = end - start; 

results:
master: 8978
this PR: 6419, about 30% faster than existing impl

[SparkQA]

Test build #134320 has finished for PR 31276 at commit 298c6fa.

• This patch fails PySpark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Kubernetes integration test starting
URL: https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder-K8s/38907/

[SparkQA]

Kubernetes integration test status success
URL: https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder-K8s/38907/

[SparkQA]

Kubernetes integration test starting
URL: https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder-K8s/38934/

[SparkQA]

Test build #134347 has finished for PR 31276 at commit e3ce5de.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Kubernetes integration test status success
URL: https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder-K8s/38934/

[zhengruifeng]

friendly ping @srowen

[srowen]

Looks OK, merge when ready.

[zhengruifeng]

Merged to master, thanks @srowen !