HBASE-5672 TestLruBlockCache#testBackgroundEvictionThread fails occasionally

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1330971 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/hadoop/hbase/io/hfile/LruBlockCache.java

@@ -572,15 +572,21 @@ public class LruBlockCache implements BlockCache, HeapSize {
     return this.stats.getEvictedCount();
   }
 
+  EvictionThread getEvictionThread() {
+    return this.evictionThread;
+  }
+
   /*
    * Eviction thread.  Sits in waiting state until an eviction is triggered
    * when the cache size grows above the acceptable level.<p>
    *
    * Thread is triggered into action by {@link LruBlockCache#runEviction()}
    */
-  private static class EvictionThread extends HasThread {
+  static class EvictionThread extends HasThread {
     private WeakReference<LruBlockCache> cache;
     private boolean go = true;
+    // flag set after enter the run method, used for test
+    private boolean enteringRun = false;
 
     public EvictionThread(LruBlockCache cache) {
       super(Thread.currentThread().getName() + ".LruBlockCache.EvictionThread");
@@ -590,6 +596,7 @@ public class LruBlockCache implements BlockCache, HeapSize {
 
     @Override
     public void run() {
+      enteringRun = true;
       while (this.go) {
         synchronized(this) {
           try {
@@ -612,6 +619,13 @@ public class LruBlockCache implements BlockCache, HeapSize {
       this.go = false;
       interrupt();
     }
+
+    /**
+     * Used for the test.
+     */
+    boolean isEnteringRun() {
+      return this.enteringRun;
+    }
   }
 
   /*

src/test/java/org/apache/hadoop/hbase/io/hfile/TestLruBlockCache.java

@@ -19,6 +19,9 @@
  */
 package org.apache.hadoop.hbase.io.hfile;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 import java.nio.ByteBuffer;
 import java.util.Collection;
 import java.util.Map;
@@ -26,19 +29,18 @@ import java.util.Random;
 
 import org.apache.hadoop.hbase.MediumTests;
 import org.apache.hadoop.hbase.io.HeapSize;
+import org.apache.hadoop.hbase.io.hfile.LruBlockCache.EvictionThread;
 import org.apache.hadoop.hbase.regionserver.metrics.SchemaMetrics;
 import org.apache.hadoop.hbase.regionserver.metrics.TestSchemaMetrics;
 import org.apache.hadoop.hbase.util.ClassSize;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
+import org.junit.experimental.categories.Category;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 import org.junit.runners.Parameterized.Parameters;
 
-import org.junit.experimental.categories.Category;
-import static org.junit.Assert.*;
-
 /**
  * Tests the concurrent LruBlockCache.<p>
  *
@@ -73,7 +75,6 @@ public class TestLruBlockCache {
 
   @Test
   public void testBackgroundEvictionThread() throws Exception {
-
     long maxSize = 100000;
     long blockSize = calculateBlockSizeDefault(maxSize, 9); // room for 9, will evict
 
@@ -81,6 +82,15 @@ public class TestLruBlockCache {
 
     CachedItem [] blocks = generateFixedBlocks(10, blockSize, "block");
 
+    EvictionThread evictionThread = cache.getEvictionThread();
+    assertTrue(evictionThread != null);
+
+    // Make sure eviction thread has entered run method
+    while (!evictionThread.isEnteringRun()) {
+      Thread.sleep(1);
+    }
+    
+
     // Add all the blocks
     for (CachedItem block : blocks) {
       cache.cacheBlock(block.cacheKey, block);