Added unit tests for size estimation for specialized hash sets and maps.

core/src/test/scala/org/apache/spark/util/collection/OpenHashMapSuite.scala

@@ -2,8 +2,20 @@ package org.apache.spark.util.collection
 
 import scala.collection.mutable.HashSet
 import org.scalatest.FunSuite
+import org.scalatest.matchers.ShouldMatchers
+import org.apache.spark.util.SizeEstimator
 
-class OpenHashMapSuite extends FunSuite {
+class OpenHashMapSuite extends FunSuite with ShouldMatchers {
+
+  test("size for specialized, primitive value (int)") {
+    val capacity = 1024
+    val map = new OpenHashMap[String, Int](capacity)
+    val actualSize = SizeEstimator.estimate(map)
+    // 64 bit for pointers, 32 bit for ints, and 1 bit for the bitset.
+    val expectedSize = capacity * (64 + 32 + 1) / 8
+    // Make sure we are not allocating a significant amount of memory beyond our expected.
+    actualSize should be <= (expectedSize * 1.1).toLong
+  }
 
   test("initialization") {
     val goodMap1 = new OpenHashMap[String, Int](1)

core/src/test/scala/org/apache/spark/util/collection/OpenHashSetSuite.scala

@@ -1,9 +1,27 @@
 package org.apache.spark.util.collection
 
 import org.scalatest.FunSuite
+import org.scalatest.matchers.ShouldMatchers
+
+import org.apache.spark.util.SizeEstimator
 
 
-class OpenHashSetSuite extends FunSuite {
+class OpenHashSetSuite extends FunSuite with ShouldMatchers {
+
+  test("size for specialized, primitive int") {
+    val loadFactor = 0.7
+    val set = new OpenHashSet[Int](64, loadFactor)
+    for (i <- 0 until 1024) {
+      set.add(i)
+    }
+    assert(set.size === 1024)
+    assert(set.capacity > 1024)
+    val actualSize = SizeEstimator.estimate(set)
+    // 32 bits for the ints + 1 bit for the bitset
+    val expectedSize = set.capacity * (32 + 1) / 8
+    // Make sure we are not allocating a significant amount of memory beyond our expected.
+    actualSize should be <= (expectedSize * 1.1).toLong
+  }
 
   test("primitive int") {
     val set = new OpenHashSet[Int]

core/src/test/scala/org/apache/spark/util/collection/PrimitiveKeyOpenHashMapSuite.scala

@@ -2,8 +2,20 @@ package org.apache.spark.util.collection
 
 import scala.collection.mutable.HashSet
 import org.scalatest.FunSuite
+import org.scalatest.matchers.ShouldMatchers
+import org.apache.spark.util.SizeEstimator
 
-class PrimitiveKeyOpenHashSetSuite extends FunSuite {
+class PrimitiveKeyOpenHashMapSuite extends FunSuite with ShouldMatchers {
+
+  test("size for specialized, primitive key, value (int, int)") {
+    val capacity = 1024
+    val map = new PrimitiveKeyOpenHashMap[Int, Int](capacity)
+    val actualSize = SizeEstimator.estimate(map)
+    // 32 bit for keys, 32 bit for values, and 1 bit for the bitset.
+    val expectedSize = capacity * (32 + 32 + 1) / 8
+    // Make sure we are not allocating a significant amount of memory beyond our expected.
+    actualSize should be <= (expectedSize * 1.1).toLong
+  }
 
   test("initialization") {
     val goodMap1 = new PrimitiveKeyOpenHashMap[Int, Int](1)