From d0b61e75ae232507ee5fbcc351da1769159a9974 Mon Sep 17 00:00:00 2001
From: Michael Stack <stack@apache.org>
Date: Tue, 8 Dec 2009 00:24:21 +0000
Subject: [PATCH] HBASE-2027 HConnectionManager.HBASE_INSTANCES leaks
 TableServers

git-svn-id: https://svn.apache.org/repos/asf/hadoop/hbase/trunk@888202 13f79535-47bb-0310-9956-ffa450edef68
---
 CHANGES.txt                                   |  2 ++
 .../hadoop/hbase/HBaseConfiguration.java      | 29 ++++++++++++++++++-
 .../hbase/client/HConnectionManager.java      | 18 ++++++++----
 3 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index ca7a7fc66f2..2e99a829a1b 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -219,6 +219,8 @@ Release 0.21.0 - Unreleased
    HBASE-2019  [EC2] remember credentials if not configured
    HBASE-2029  Reduce shell exception dump on console
                (Lars George and J-D via Stack)
+   HBASE-2027  HConnectionManager.HBASE_INSTANCES leaks TableServers
+               (Dave Latham via Stack)
 
   NEW FEATURES
    HBASE-1901  "General" partitioner for "hbase-48" bulk (behind the api, write
diff --git a/src/java/org/apache/hadoop/hbase/HBaseConfiguration.java b/src/java/org/apache/hadoop/hbase/HBaseConfiguration.java
index 4b54c36671c..03e65aa83d2 100644
--- a/src/java/org/apache/hadoop/hbase/HBaseConfiguration.java
+++ b/src/java/org/apache/hadoop/hbase/HBaseConfiguration.java
@@ -52,7 +52,7 @@ public class HBaseConfiguration extends Configuration {
   
   /**
    * Returns the hash code value for this HBaseConfiguration. The hash code of a
-   * HBaseConfiguration is defined by the sum of the hash codes of its entries.
+   * HBaseConfiguration is defined by the xor of the hash codes of its entries.
    * 
    * @see Configuration#iterator() How the entries are obtained.
    */
@@ -66,5 +66,32 @@ public class HBaseConfiguration extends Configuration {
     }
     return hash;
   }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj)
+      return true;
+    if (obj == null)
+      return false;
+    if (!(obj instanceof HBaseConfiguration))
+      return false;
+    
+    HBaseConfiguration otherConf = (HBaseConfiguration) obj;
+    if (size() != otherConf.size()) {
+      return false;
+    }
+    Iterator<Entry<String, String>> propertyIterator = this.iterator();
+    while (propertyIterator.hasNext()) {
+      Entry<String, String> entry = propertyIterator.next();
+      String key = entry.getKey();
+      String value = entry.getValue();
+      if (!value.equals(otherConf.getRaw(key))) {
+        return false;
+      }
+    }
+    
+    return true;
+  }
+  
   
 }
diff --git a/src/java/org/apache/hadoop/hbase/client/HConnectionManager.java b/src/java/org/apache/hadoop/hbase/client/HConnectionManager.java
index 33aa73378ff..12124fc441d 100644
--- a/src/java/org/apache/hadoop/hbase/client/HConnectionManager.java
+++ b/src/java/org/apache/hadoop/hbase/client/HConnectionManager.java
@@ -24,10 +24,10 @@ import java.lang.reflect.UndeclaredThrowableException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeSet;
-import java.util.WeakHashMap;
 import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.commons.logging.Log;
@@ -85,12 +85,20 @@ public class HConnectionManager implements HConstants {
     super();
   }
   
-  // A Map of master HBaseConfiguration -> connection information for that 
-  // instance. Note that although the Map is synchronized, the objects it 
-  // contains are mutable and hence require synchronized access to them
+  private static final int MAX_CACHED_HBASE_INSTANCES=31;
+  // A LRU Map of master HBaseConfiguration -> connection information for that 
+  // instance. The objects it contains are mutable and hence require
+  // synchronized access to them.  We set instances to 31.  The zk default max
+  // connections is 30 so should run into zk issues before hit this value of 31.
   private static 
   final Map<HBaseConfiguration, TableServers> HBASE_INSTANCES =
-    new WeakHashMap<HBaseConfiguration, TableServers>();
+    new LinkedHashMap<HBaseConfiguration, TableServers>
+      ((int) (MAX_CACHED_HBASE_INSTANCES/0.75F)+1, 0.75F, true) {
+      @Override
+      protected boolean removeEldestEntry(Map.Entry<HBaseConfiguration, TableServers> eldest) {
+        return size() > MAX_CACHED_HBASE_INSTANCES;
+      }
+  };
   
   private static final Map<String, ClientZKWatcher> ZK_WRAPPERS = 
     new HashMap<String, ClientZKWatcher>();