From 6bf967adfb53001365bf4f9d5a72a1e095ee2900 Mon Sep 17 00:00:00 2001
From: Zach York <zyork@amazon.com>
Date: Wed, 28 Feb 2018 10:40:38 -0800
Subject: [PATCH] [HBASE-20141] Fix TooManyFiles exception when
 RefreshingChannels

HBASE-19435 implements a fix for reopening file channels when they are unnexpected closed
to avoid disabling the BucketCache. However, it was missed that the the channels might not
actually be completely closed (the write or read channel might still be open
(see https://docs.oracle.com/javase/7/docs/api/java/nio/channels/ClosedChannelException.html)
This commit closes any open channels before creating a new channel.
---
 .../hadoop/hbase/io/hfile/bucket/FileIOEngine.java  | 13 +++++++++++--
 .../hbase/io/hfile/bucket/TestFileIOEngine.java     | 11 +++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/FileIOEngine.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/FileIOEngine.java
index cf963f0f0c3..648d4bca7b7 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/FileIOEngine.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/FileIOEngine.java
@@ -19,7 +19,6 @@
 package org.apache.hadoop.hbase.io.hfile.bucket;
 
 import java.io.File;
-import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.nio.ByteBuffer;
@@ -274,7 +273,17 @@ public class FileIOEngine implements IOEngine {
     return fileNum;
   }
 
-  private void refreshFileConnection(int accessFileNum) throws FileNotFoundException {
+  @VisibleForTesting
+  FileChannel[] getFileChannels() {
+    return fileChannels;
+  }
+
+  @VisibleForTesting
+  void refreshFileConnection(int accessFileNum) throws IOException {
+    FileChannel fileChannel = fileChannels[accessFileNum];
+    if (fileChannel != null) {
+      fileChannel.close();
+    }
     rafs[accessFileNum] = new RandomAccessFile(filePaths[accessFileNum], "rw");
     fileChannels[accessFileNum] = rafs[accessFileNum].getChannel();
   }
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestFileIOEngine.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestFileIOEngine.java
index 508626539d2..648098667e5 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestFileIOEngine.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestFileIOEngine.java
@@ -18,10 +18,13 @@
 package org.apache.hadoop.hbase.io.hfile.bucket;
 
 import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
 
 import java.io.File;
 import java.io.IOException;
 import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
 import java.util.ArrayList;
 import java.util.List;
 import org.apache.hadoop.hbase.HBaseClassTestRule;
@@ -138,4 +141,12 @@ public class TestFileIOEngine {
     ByteBuff data2 = deserializer.getDeserializedByteBuff();
     assertArrayEquals(data1, data2.array());
   }
+
+  @Test
+  public void testRefreshFileConnectionClosesConnections() throws IOException {
+    FileChannel fileChannel = fileIOEngine.getFileChannels()[0];
+    assertNotNull(fileChannel);
+    fileIOEngine.refreshFileConnection(0);
+    assertFalse(fileChannel.isOpen());
+  }
 }