Remove hacky test.

Author: viirya

sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFileFormatSuite.scala

@@ -26,22 +26,6 @@ import org.apache.spark.sql.test.SharedSQLContext
 
 class ParquetFileFormatSuite extends QueryTest with ParquetTest with SharedSQLContext {
 
-  test("Number of threads doesn't grow extremely after parquet file reading") {
-    withTempDir { dir =>
-      val file = dir.toString + "/file"
-      spark.range(1).toDF("a").coalesce(1).write.parquet(file)
-      spark.read.parquet(file)
-      val numThreadBefore = Thread.activeCount
-      (1 to 100).map { _ =>
-        spark.read.parquet(file)
-      }
-      val numThreadAfter = Thread.activeCount
-      // Hard to test a correct thread number,
-      // but it shouldn't increase more than a reasonable number.
-      assert(numThreadAfter - numThreadBefore < 20)
-    }
-  }
-
   test("read parquet footers in parallel") {
     def testReadFooters(ignoreCorruptFiles: Boolean): Unit = {
       withTempDir { dir =>