From 74adb11f4c504abbb6a52de72b53883ad7b952b4 Mon Sep 17 00:00:00 2001
From: tedyu <yuzhihong@gmail.com>
Date: Fri, 23 Jan 2015 09:43:01 -0800
Subject: [PATCH] HBASE-10499 In write heavy scenario one of the regions does
 not get flushed causing RegionTooBusyException (Ram and Ted)

---
 .../hbase/regionserver/MemStoreFlusher.java       | 15 +++++++++++----
 .../hbase/regionserver/TestFlushRegionEntry.java  |  5 +++--
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreFlusher.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreFlusher.java
index a345a05e64d..e5ad5908cb8 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreFlusher.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreFlusher.java
@@ -619,7 +619,8 @@ class MemStoreFlusher implements FlushRequester {
     return this.globalMemStoreLimit;
   }
 
-  interface FlushQueueEntry extends Delayed {}
+  interface FlushQueueEntry extends Delayed {
+  }
 
   /**
    * Token to insert into the flush queue that ensures that the flusher does not sleep
@@ -639,7 +640,6 @@ class MemStoreFlusher implements FlushRequester {
     public boolean equals(Object obj) {
       return (this == obj);
     }
-
   }
 
   /**
@@ -709,8 +709,14 @@ class MemStoreFlusher implements FlushRequester {
 
     @Override
     public int compareTo(Delayed other) {
-      return Long.valueOf(getDelay(TimeUnit.MILLISECONDS) -
+      // Delay is compared first. If there is a tie, compare region's hash code
+      int ret = Long.valueOf(getDelay(TimeUnit.MILLISECONDS) -
         other.getDelay(TimeUnit.MILLISECONDS)).intValue();
+      if (ret != 0) {
+        return ret;
+      }
+      FlushQueueEntry otherEntry = (FlushQueueEntry) other;
+      return hashCode() - otherEntry.hashCode();
     }
 
     @Override
@@ -720,7 +726,8 @@ class MemStoreFlusher implements FlushRequester {
 
     @Override
     public int hashCode() {
-      return (int) getDelay(TimeUnit.MILLISECONDS);
+      int hash = (int) getDelay(TimeUnit.MILLISECONDS);
+      return hash ^ region.hashCode();
     }
 
    @Override
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestFlushRegionEntry.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestFlushRegionEntry.java
index 676885b61ed..bd50f5912d6 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestFlushRegionEntry.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestFlushRegionEntry.java
@@ -34,8 +34,9 @@ public class TestFlushRegionEntry {
 
   @Test
   public void test() {
-    FlushRegionEntry entry = new FlushRegionEntry(Mockito.mock(HRegion.class), true);
-    FlushRegionEntry other = new FlushRegionEntry(Mockito.mock(HRegion.class), true);
+    HRegion r = Mockito.mock(HRegion.class);
+    FlushRegionEntry entry = new FlushRegionEntry(r, true);
+    FlushRegionEntry other = new FlushRegionEntry(r, true);
 
     assertEquals(entry.hashCode(), other.hashCode());
     assertEquals(entry, other);