[SPARK-20407][TESTS] ParquetQuerySuite 'Enabling/disabling ignoreCorruptFiles' flaky test

## What changes were proposed in this pull request?

SharedSQLContext.afterEach now calls DebugFilesystem.assertNoOpenStreams inside eventually.
SQLTestUtils withTempDir calls waitForTasksToFinish before deleting the directory.

## How was this patch tested?
Added new test in ParquetQuerySuite based on the flaky test

Author: Bogdan Raducanu <bogdan@databricks.com>

Closes #17701 from bogdanrdc/SPARK-20407.

1 files changed, 9 insertions, 4 deletions

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/test/SharedSQLContext.scala b/sql/core/src/test/scala/org/apache/spark/sql/test/SharedSQLContext.scala
index e122b39f6f..3d76e05f61 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/test/SharedSQLContext.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/test/SharedSQLContext.scala
@@ -17,17 +17,18 @@
 
 package org.apache.spark.sql.test
 
+import scala.concurrent.duration._
+
 import org.scalatest.BeforeAndAfterEach
+import org.scalatest.concurrent.Eventually
 
 import org.apache.spark.{DebugFilesystem, SparkConf}
 import org.apache.spark.sql.{SparkSession, SQLContext}
-import org.apache.spark.sql.internal.SQLConf
-
 
 /**
  * Helper trait for SQL test suites where all tests share a single [[TestSparkSession]].
  */
-trait SharedSQLContext extends SQLTestUtils with BeforeAndAfterEach {
+trait SharedSQLContext extends SQLTestUtils with BeforeAndAfterEach with Eventually {
 
   protected val sparkConf = new SparkConf()
 
@@ -84,6 +85,10 @@ trait SharedSQLContext extends SQLTestUtils with BeforeAndAfterEach {
 
   protected override def afterEach(): Unit = {
     super.afterEach()
-    DebugFilesystem.assertNoOpenStreams()
+    // files can be closed from other threads, so wait a bit
+    // normally this doesn't take more than 1s
+    eventually(timeout(10.seconds)) {
+      DebugFilesystem.assertNoOpenStreams()
+    }
   }
 }