From 281742abc45b85946fcddc608aa7dad4b3bec89e Mon Sep 17 00:00:00 2001
From: wenshao <szujobs@hotmail.com>
Date: Sat, 7 Oct 2017 12:09:02 +0800
Subject: [PATCH] add syncrhonized for SelectListCache.

---
 .../com/alibaba/druid/sql/parser/SQLSelectListCache.java  | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/main/java/com/alibaba/druid/sql/parser/SQLSelectListCache.java b/src/main/java/com/alibaba/druid/sql/parser/SQLSelectListCache.java
index b4b73c35b0..be51740303 100644
--- a/src/main/java/com/alibaba/druid/sql/parser/SQLSelectListCache.java
+++ b/src/main/java/com/alibaba/druid/sql/parser/SQLSelectListCache.java
@@ -25,15 +25,15 @@ import java.util.concurrent.CopyOnWriteArrayList;
 
 public class SQLSelectListCache {
     private final String dbType;
-    private List<String> sqlCache = new CopyOnWriteArrayList<String>();
-    private List<SQLSelectQueryBlock> queryBlockCache = new CopyOnWriteArrayList<SQLSelectQueryBlock>();
-    private List<String> printSqlList = new ArrayList<String>();
+    private final List<String> sqlCache = new ArrayList<String>();
+    private final List<SQLSelectQueryBlock> queryBlockCache = new ArrayList<SQLSelectQueryBlock>();
+    private final List<String> printSqlList = new ArrayList<String>();
 
     public SQLSelectListCache(String dbType) {
         this.dbType = dbType;
     }
 
-    public void add(String select) {
+    public synchronized void add(String select) {
         if (select == null || select.length() == 0) {
             return;
         }