From f09710bbb8e56d066f9d7a2e70a41ed82d5aa781 Mon Sep 17 00:00:00 2001
From: Ayush Saxena <ayushsaxena@apache.org>
Date: Wed, 12 Feb 2020 20:22:51 +0530
Subject: [PATCH] HDFS-15161. When evictableMmapped or evictable size is zero,
 do not throw NoSuchElementException in ShortCircuitCache#close(). Contributed
 by Lisheng Sun

---
 .../hdfs/shortcircuit/ShortCircuitCache.java  | 23 +++++--------------
 1 file changed, 6 insertions(+), 17 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/shortcircuit/ShortCircuitCache.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/shortcircuit/ShortCircuitCache.java
index d3eb3ac0da..d4d898c892 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/shortcircuit/ShortCircuitCache.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/shortcircuit/ShortCircuitCache.java
@@ -26,7 +26,6 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
-import java.util.NoSuchElementException;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
@@ -865,23 +864,13 @@ public void close() {
       // Close and join cacheCleaner thread.
       IOUtilsClient.cleanupWithLogger(LOG, cacheCleaner);
       // Purge all replicas.
-      while (true) {
-        Object eldestKey;
-        try {
-          eldestKey = evictable.firstKey();
-        } catch (NoSuchElementException e) {
-          break;
-        }
-        purge((ShortCircuitReplica)evictable.get(eldestKey));
+      while (!evictable.isEmpty()) {
+        Object eldestKey = evictable.firstKey();
+        purge((ShortCircuitReplica) evictable.get(eldestKey));
       }
-      while (true) {
-        Object eldestKey;
-        try {
-          eldestKey = evictableMmapped.firstKey();
-        } catch (NoSuchElementException e) {
-          break;
-        }
-        purge((ShortCircuitReplica)evictableMmapped.get(eldestKey));
+      while (!evictableMmapped.isEmpty()) {
+        Object eldestKey = evictableMmapped.firstKey();
+        purge((ShortCircuitReplica) evictableMmapped.get(eldestKey));
       }
     } finally {
       lock.unlock();