From d521b7a30721e1dc1753f432ebd1cfde93a29658 Mon Sep 17 00:00:00 2001
From: "Ma,Gang" <ganma@ebay.com>
Date: Wed, 11 May 2016 15:26:19 +0800
Subject: [PATCH] Fix bug KYLIN-1676:High CPU in TrieDictionary due to
 incorrect use of HashMap

---
 .../src/main/java/org/apache/kylin/dict/TrieDictionary.java       | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/core-dictionary/src/main/java/org/apache/kylin/dict/TrieDictionary.java b/core-dictionary/src/main/java/org/apache/kylin/dict/TrieDictionary.java
index 3a05d0a..233d18e 100644
--- a/core-dictionary/src/main/java/org/apache/kylin/dict/TrieDictionary.java
+++ b/core-dictionary/src/main/java/org/apache/kylin/dict/TrieDictionary.java
@@ -29,7 +29,9 @@ import java.io.*;
 import java.lang.ref.SoftReference;
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.Map;
 import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * A dictionary based on Trie data structure that maps enumerations of byte[] to
@@ -73,7 +75,7 @@ public class TrieDictionary<T> extends Dictionary<T> {
     transient private int firstByteOffset;
 
     transient private boolean enableValueCache = true;
-    transient private SoftReference<HashMap> valueToIdCache;
+    transient private SoftReference<Map> valueToIdCache;
     transient private SoftReference<Object[]> idToValueCache;
 
     transient private boolean enableIdToValueBytesCache = false;
@@ -117,7 +119,7 @@ public class TrieDictionary<T> extends Dictionary<T> {
         }
 
         if (enableValueCache) {
-            valueToIdCache = new SoftReference<HashMap>(new HashMap());
+            valueToIdCache = new SoftReference<Map>(new ConcurrentHashMap());
             idToValueCache = new SoftReference<Object[]>(new Object[nValues]);
         }
     }
@@ -145,7 +147,7 @@ public class TrieDictionary<T> extends Dictionary<T> {
     @Override
     final protected int getIdFromValueImpl(T value, int roundingFlag) {
         if (enableValueCache && roundingFlag == 0) {
-            HashMap cache = valueToIdCache.get(); // SoftReference to skip cache gracefully when short of memory
+            Map cache = valueToIdCache.get(); // SoftReference to skip cache gracefully when short of memory
             if (cache != null) {
                 Integer id = null;
                 id = (Integer) cache.get(value);
-- 
2.6.4