From 5ffcc11a4bce8f69d911fb700c90d2aeddbad8e7 Mon Sep 17 00:00:00 2001
From: Jeff Zhang <zjffdu@apache.org>
Date: Sun, 22 Apr 2018 11:46:53 +0800
Subject: [PATCH] ZEPPELIN-3401. Deadlock while restarting interpreter

---
 .../src/main/java/org/apache/zeppelin/notebook/Note.java    | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/Note.java b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/Note.java
index 664e986e45c..b83954c9563 100644
--- a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/Note.java
+++ b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/Note.java
@@ -101,6 +101,7 @@ public class Note implements ParagraphJobListener, JsonSerializable {
   private transient NotebookRepo repo;
   private transient SearchService index;
   private transient ScheduledFuture delayedPersist;
+  private transient Object delayedPersistLock = new Object();
   private transient NoteEventListener noteEventListener;
   private transient Credentials credentials;
   private transient NoteNameListener noteNameListener;
@@ -852,7 +853,7 @@ public Note getUserNote(String user) {
   }
 
   private void startDelayedPersistTimer(int maxDelaySec, final AuthenticationInfo subject) {
-    synchronized (this) {
+    synchronized (delayedPersistLock) {
       if (delayedPersist != null) {
         return;
       }
@@ -872,11 +873,10 @@ public void run() {
   }
 
   private void stopDelayedPersistTimer() {
-    synchronized (this) {
+    synchronized (delayedPersistLock) {
       if (delayedPersist == null) {
         return;
       }
-
       delayedPersist.cancel(false);
     }
   }