From cb3e3787820fb25dc0412585cf810927731e5bb8 Mon Sep 17 00:00:00 2001
From: Mukund Thakur <mthakur@cloudera.com>
Date: Thu, 16 Jul 2020 22:39:59 +0530
Subject: [PATCH] HADOOP-17130. Configuration.getValByRegex() shouldn't be
 updating the results while fetching. (#2142)

Contributed by Mukund Thakur

Change-Id: I35fe671d4026e8d3c04fc52012c3edcd4495e14a
---
 .../src/main/java/org/apache/hadoop/conf/Configuration.java | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
index e0111efc25e..5a708a882f6 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
@@ -3828,6 +3828,7 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
     Pattern p = Pattern.compile(regex);
 
     Map<String,String> result = new HashMap<String,String>();
+    List<String> resultKeys = new ArrayList<>();
     Matcher m;
 
     for(Map.Entry<Object,Object> item: getProps().entrySet()) {
@@ -3835,11 +3836,12 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
           item.getValue() instanceof String) {
         m = p.matcher((String)item.getKey());
         if(m.find()) { // match
-          result.put((String) item.getKey(),
-              substituteVars(getProps().getProperty((String) item.getKey())));
+          resultKeys.add((String) item.getKey());
         }
       }
     }
+    resultKeys.forEach(item ->
+            result.put(item, substituteVars(getProps().getProperty(item))));
     return result;
   }