Fixes race condition in CliSuite

Author: liancheng

sql/hive-thriftserver/src/test/scala/org/apache/spark/sql/hive/thriftserver/CliSuite.scala

@@ -18,19 +18,17 @@
 
 package org.apache.spark.sql.hive.thriftserver
 
+import java.io._
+
 import scala.collection.mutable.ArrayBuffer
-import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.duration._
-import scala.concurrent.{Await, Future, Promise}
+import scala.concurrent.{Await, Promise}
 import scala.sys.process.{Process, ProcessLogger}
 
-import java.io._
-import java.util.concurrent.atomic.AtomicInteger
-
 import org.apache.hadoop.hive.conf.HiveConf.ConfVars
 import org.scalatest.{BeforeAndAfterAll, FunSuite}
 
-import org.apache.spark.{SparkException, Logging}
+import org.apache.spark.Logging
 import org.apache.spark.sql.catalyst.util.getTempFilePath
 
 class CliSuite extends FunSuite with BeforeAndAfterAll with Logging {
@@ -53,23 +51,20 @@ class CliSuite extends FunSuite with BeforeAndAfterAll with Logging {
        """.stripMargin.split("\\s+").toSeq ++ extraArgs
     }
 
-    // AtomicInteger is needed because stderr and stdout of the forked process are handled in
-    // different threads.
-    val next = new AtomicInteger(0)
+    var next = 0
     val foundAllExpectedAnswers = Promise.apply[Unit]()
     val queryStream = new ByteArrayInputStream(queries.mkString("\n").getBytes)
     val buffer = new ArrayBuffer[String]()
+    val lock = new Object
 
-    def captureOutput(source: String)(line: String) {
+    def captureOutput(source: String)(line: String): Unit = lock.synchronized {
       buffer += s"$source> $line"
-      // If we haven't found all expected answers...
-      if (next.get() < expectedAnswers.size) {
-        // If another expected answer is found...
-        if (line.startsWith(expectedAnswers(next.get()))) {
-          // If all expected answers have been found...
-          if (next.incrementAndGet() == expectedAnswers.size) {
-            foundAllExpectedAnswers.trySuccess(())
-          }
+      // If we haven't found all expected answers and another expected answer comes up...
+      if (next < expectedAnswers.size && line.startsWith(expectedAnswers(next))) {
+        next += 1
+        // If all expected answers have been found...
+        if (next == expectedAnswers.size) {
+          foundAllExpectedAnswers.trySuccess(())
         }
       }
     }
@@ -88,8 +83,8 @@ class CliSuite extends FunSuite with BeforeAndAfterAll with Logging {
            |=======================
            |Spark SQL CLI command line: ${command.mkString(" ")}
            |
-           |Executed query ${next.get()} "${queries(next.get())}",
-           |But failed to capture expected output "${expectedAnswers(next.get())}" within $timeout.
+           |Executed query $next "${queries(next)}",
+           |But failed to capture expected output "${expectedAnswers(next)}" within $timeout.
            |
            |${buffer.mkString("\n")}
            |===========================