[SPARK-6618][SQL] HiveMetastoreCatalog.lookupRelation should use fine-grained lock

JIRA: https://issues.apache.org/jira/browse/SPARK-6618

Author: Yin Huai <yhuai@databricks.com>

Closes #5281 from yhuai/lookupRelationLock and squashes the following commits:

591b4be [Yin Huai] A test?
b3a9625 [Yin Huai] Just protect client.

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala

@@ -172,12 +172,16 @@ private[hive] class HiveMetastoreCatalog(hive: HiveContext) extends Catalog with
 
   def lookupRelation(
       tableIdentifier: Seq[String],
-      alias: Option[String]): LogicalPlan = synchronized {
+      alias: Option[String]): LogicalPlan = {
     val tableIdent = processTableIdentifier(tableIdentifier)
     val databaseName = tableIdent.lift(tableIdent.size - 2).getOrElse(
       hive.sessionState.getCurrentDatabase)
     val tblName = tableIdent.last
-    val table = try client.getTable(databaseName, tblName) catch {
+    val table = try {
+      synchronized {
+        client.getTable(databaseName, tblName)
+      }
+    } catch {
       case te: org.apache.hadoop.hive.ql.metadata.InvalidTableException =>
         throw new NoSuchTableException
     }
@@ -199,7 +203,9 @@ private[hive] class HiveMetastoreCatalog(hive: HiveContext) extends Catalog with
     } else {
       val partitions: Seq[Partition] =
         if (table.isPartitioned) {
-          HiveShim.getAllPartitionsOf(client, table).toSeq
+          synchronized {
+            HiveShim.getAllPartitionsOf(client, table).toSeq
+          }
         } else {
           Nil
         }

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala

@@ -433,4 +433,15 @@ class SQLQuerySuite extends QueryTest {
     dropTempTable("data")
     setConf("spark.sql.hive.convertCTAS", originalConf)
   }
+
+  test("sanity test for SPARK-6618") {
+    (1 to 100).par.map { i =>
+      val tableName = s"SPARK_6618_table_$i"
+      sql(s"CREATE TABLE $tableName (col1 string)")
+      catalog.lookupRelation(Seq(tableName))
+      table(tableName)
+      tables()
+      sql(s"DROP TABLE $tableName")
+    }
+  }
 }