diff --git a/mllib/src/main/scala/org/apache/spark/ml/clustering/GaussianMixture.scala b/mllib/src/main/scala/org/apache/spark/ml/clustering/GaussianMixture.scala
index 64ecc1ebda589..214973f7396dc 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/clustering/GaussianMixture.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/clustering/GaussianMixture.scala
@@ -341,7 +341,7 @@ class GaussianMixture @Since("2.0.0") (
     val sc = dataset.sparkSession.sparkContext
     val numClusters = $(k)
 
-    val instances: RDD[Vector] = dataset
+    val instances = dataset
       .select(DatasetUtils.columnToVector(dataset, getFeaturesCol)).rdd.map {
       case Row(features: Vector) => features
     }.cache()
@@ -416,6 +416,7 @@ class GaussianMixture @Since("2.0.0") (
       iter += 1
     }
 
+    instances.unpersist(false)
     val gaussianDists = gaussians.map { case (mean, covVec) =>
       val cov = GaussianMixture.unpackUpperTriangularMatrix(numFeatures, covVec.values)
       new MultivariateGaussian(mean, cov)