use ConcurrentHashMap in sql conf, intead synchronizedMap

Author: scwf

sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala

@@ -50,8 +50,8 @@ private[spark] object SQLConf {
 trait SQLConf {
   import SQLConf._
 
-  @transient protected[spark] val settings = java.util.Collections.synchronizedMap(
-    new java.util.HashMap[String, String]())
+  @transient protected[spark] val settings =
+    new java.util.concurrent.ConcurrentHashMap[String, String]
 
   /** ************************ Spark SQL Params/Hints ******************* */
   // TODO: refactor so that these hints accessors don't pollute the name space of SQLContext?

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

@@ -473,7 +473,7 @@ class HiveQuerySuite extends HiveComparisonTest {
 
     sql(s"SET ${testKey + testKey}=${testVal + testVal}")
     assert(hiveconf.get(testKey + testKey, "") == testVal + testVal)
-    assertResult(Array(s"$testKey=$testVal", s"${testKey + testKey}=${testVal + testVal}")) {
+    assertResult(Array( s"${testKey + testKey}=${testVal + testVal}", s"$testKey=$testVal")) {
       sql(s"SET").collect().map(_.getString(0))
     }
 
@@ -501,7 +501,7 @@ class HiveQuerySuite extends HiveComparisonTest {
 
     sql(s"SET ${testKey + testKey}=${testVal + testVal}")
     assert(hiveconf.get(testKey + testKey, "") == testVal + testVal)
-    assertResult(Array(s"$testKey=$testVal", s"${testKey + testKey}=${testVal + testVal}")) {
+    assertResult(Array(s"${testKey + testKey}=${testVal + testVal}", s"$testKey=$testVal")) {
       sql("SET").collect().map(_.getString(0))
     }