diff --git a/src/main/scala/yaooqinn/kyuubi/operation/OperationManager.scala b/src/main/scala/yaooqinn/kyuubi/operation/OperationManager.scala
index 030082b53..b236dbe73 100644
--- a/src/main/scala/yaooqinn/kyuubi/operation/OperationManager.scala
+++ b/src/main/scala/yaooqinn/kyuubi/operation/OperationManager.scala
@@ -148,12 +148,12 @@ private[kyuubi] class OperationManager private(name: String)
     }
     try {
       // read logs
-      val logs = operationLog.readOperationLog(isFetchFirst(orientation), maxRows)
+      val logs = operationLog.readOperationLog(isFetchFirst(orientation), maxRows).asScala
       // convert logs to RowSet
       val tableSchema: TableSchema = new TableSchema(getLogSchema)
       val rowSet: RowSet =
         RowSetFactory.create(tableSchema, getOperation(opHandle).getProtocolVersion)
-      for (log <- logs.asScala) {
+      for (log <- logs) {
         rowSet.addRow(Array[AnyRef](log))
       }
       rowSet
@@ -163,6 +163,10 @@ private[kyuubi] class OperationManager private(name: String)
     }
   }
 
+  def getResultSetSchema(opHandle: OperationHandle): TableSchema = {
+    getOperation(opHandle).getResultSetSchema
+  }
+
   private[this] def isFetchFirst(fetchOrientation: FetchOrientation): Boolean = {
     fetchOrientation == FetchOrientation.FETCH_FIRST
   }
diff --git a/src/main/scala/yaooqinn/kyuubi/server/BackendService.scala b/src/main/scala/yaooqinn/kyuubi/server/BackendService.scala
index 6be6ed8e6..d47ef1dd0 100644
--- a/src/main/scala/yaooqinn/kyuubi/server/BackendService.scala
+++ b/src/main/scala/yaooqinn/kyuubi/server/BackendService.scala
@@ -141,15 +141,15 @@ private[server] class BackendService private(name: String)
   }
 
   override def cancelOperation(opHandle: OperationHandle): Unit = {
-    sessionManager.getOperationMgr.getOperation(opHandle).cancel()
+    sessionManager.getOperationMgr.getOperation(opHandle).getSession.cancelOperation(opHandle)
   }
 
   override def closeOperation(opHandle: OperationHandle): Unit = {
-    sessionManager.getOperationMgr.getOperation(opHandle).close()
+    sessionManager.getOperationMgr.getOperation(opHandle).getSession.closeOperation(opHandle)
   }
 
   override def getResultSetMetadata(opHandle: OperationHandle): TableSchema = {
-    sessionManager.getOperationMgr.getOperation(opHandle).getResultSetSchema
+    sessionManager.getOperationMgr.getOperation(opHandle).getSession.getResultSetMetadata(opHandle)
   }
 
   override def fetchResults(opHandle: OperationHandle): RowSet = {
diff --git a/src/main/scala/yaooqinn/kyuubi/session/KyuubiSession.scala b/src/main/scala/yaooqinn/kyuubi/session/KyuubiSession.scala
index 2e3cb7b84..3f5b331bf 100644
--- a/src/main/scala/yaooqinn/kyuubi/session/KyuubiSession.scala
+++ b/src/main/scala/yaooqinn/kyuubi/session/KyuubiSession.scala
@@ -116,7 +116,7 @@ private[kyuubi] class KyuubiSession(
   }
 
   private[this] def startSparkContextInNewThread(): Unit = {
-    new Thread("name") {
+    new Thread(s"Start-SparkContext-$getUserName") {
       override def run(): Unit = {
         promisedSparkContext.trySuccess(new SparkContext(conf))
       }
@@ -316,7 +316,7 @@ private[kyuubi] class KyuubiSession(
     try {
       // Iterate through the opHandles and close their operations
       for (opHandle <- opHandleSet) {
-        operationManager.closeOperation(opHandle)
+        closeOperation(opHandle)
       }
       opHandleSet.clear()
       // Cleanup session log directory.
@@ -338,8 +338,7 @@ private[kyuubi] class KyuubiSession(
     acquire(true)
     try {
       operationManager.cancelOperation(opHandle)
-    }
-    finally {
+    } finally {
       release(true)
     }
   }
@@ -357,7 +356,7 @@ private[kyuubi] class KyuubiSession(
   def getResultSetMetadata(opHandle: OperationHandle): TableSchema = {
     acquire(true)
     try {
-      operationManager.getOperation(opHandle).getResultSetSchema
+      operationManager.getResultSetSchema(opHandle)
     } finally {
       release(true)
     }
@@ -408,7 +407,8 @@ private[kyuubi] class KyuubiSession(
    * @param operationLogRootDir the parent dir of the session dir
    */
   def setOperationLogSessionDir(operationLogRootDir: File): Unit = {
-    sessionLogDir = new File(operationLogRootDir, sessionHandle.getHandleIdentifier.toString)
+    sessionLogDir = new File(operationLogRootDir,
+      username + File.separator + sessionHandle.getHandleIdentifier.toString)
     _isOperationLogEnabled = true
     if (!sessionLogDir.exists) {
       if (!sessionLogDir.mkdirs) {
diff --git a/src/main/scala/yaooqinn/kyuubi/session/SessionManager.scala b/src/main/scala/yaooqinn/kyuubi/session/SessionManager.scala
index 9046b217e..6e7be3c25 100644
--- a/src/main/scala/yaooqinn/kyuubi/session/SessionManager.scala
+++ b/src/main/scala/yaooqinn/kyuubi/session/SessionManager.scala
@@ -18,12 +18,12 @@
 package yaooqinn.kyuubi.session
 
 import java.io.{File, IOException}
-import java.util.{Date, Map => JMap}
+import java.util.Date
 import java.util.concurrent._
 import java.util.concurrent.atomic.AtomicInteger
 
 import scala.collection.JavaConverters._
-import scala.collection.mutable.HashSet
+import scala.collection.mutable.{HashSet => MHSet}
 
 import org.apache.commons.io.FileUtils
 import org.apache.hive.service.cli.{HiveSQLException, SessionHandle}
@@ -49,7 +49,7 @@ private[kyuubi] class SessionManager private(
   private[this] val handleToSessionUser = new ConcurrentHashMap[SessionHandle, String]
   private[this] val userToSparkSession =
     new ConcurrentHashMap[String, (SparkSession, AtomicInteger)]
-  private[this] val userSparkContextBeingConstruct = new HashSet[String]()
+  private[this] val userSparkContextBeingConstruct = new MHSet[String]()
   private[this] var execPool: ThreadPoolExecutor = _
   private[this] var isOperationLogEnabled = false
   private[this] var operationLogRootDir: File = _