HBASE-18451 PeriodicMemstoreFlusher should inspect the queue before adding a delayed flush request, fix logging

Signed-off-by: Andrew Purtell <apurtell@apache.org>

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/FlushRequester.java

@@ -32,8 +32,9 @@ public interface FlushRequester {
    * @param region the Region requesting the cache flush
    * @param forceFlushAllStores whether we want to flush all stores. e.g., when request from log
    *          rolling.
+   * @return true if our region is added into the queue, false otherwise
    */
-  void requestFlush(HRegion region, boolean forceFlushAllStores, FlushLifeCycleTracker tracker);
+  boolean requestFlush(HRegion region, boolean forceFlushAllStores, FlushLifeCycleTracker tracker);
 
   /**
    * Tell the listener the cache needs to be flushed after a delay
@@ -42,8 +43,9 @@ public interface FlushRequester {
    * @param delay after how much time should the flush happen
    * @param forceFlushAllStores whether we want to flush all stores. e.g., when request from log
    *          rolling.
+   * @return true if our region is added into the queue, false otherwise
    */
-  void requestDelayedFlush(HRegion region, long delay, boolean forceFlushAllStores);
+  boolean requestDelayedFlush(HRegion region, long delay, boolean forceFlushAllStores);
 
   /**
    * Register a FlushRequestListener

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java

@@ -1753,14 +1753,14 @@ public class HRegionServer extends HasThread implements
           FlushRequester requester = server.getFlushRequester();
           if (requester != null) {
             long randomDelay = (long) RandomUtils.nextInt(0, RANGE_OF_DELAY) + MIN_DELAY_TIME;
-            LOG.info(getName() + " requesting flush of " +
-              r.getRegionInfo().getRegionNameAsString() + " because " +
-              whyFlush.toString() +
-              " after random delay " + randomDelay + "ms");
             //Throttle the flushes by putting a delay. If we don't throttle, and there
             //is a balanced write-load on the regions in a table, we might end up
             //overwhelming the filesystem with too many flushes at once.
-            requester.requestDelayedFlush(r, randomDelay, false);
+            if (requester.requestDelayedFlush(r, randomDelay, false)) {
+              LOG.info("{} requesting flush of {} because {} after random delay {} ms",
+                  getName(), r.getRegionInfo().getRegionNameAsString(),  whyFlush.toString(),
+                  randomDelay);
+            }
           }
         }
       }

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreFlusher.java

@@ -455,8 +455,8 @@ class MemStoreFlusher implements FlushRequester {
   }
 
   @Override
-  public void requestFlush(HRegion r, boolean forceFlushAllStores, FlushLifeCycleTracker tracker) {
+  public boolean requestFlush(HRegion r, boolean forceFlushAllStores,
-    r.incrementFlushesQueuedCount();
+                              FlushLifeCycleTracker tracker) {
     synchronized (regionsInQueue) {
       if (!regionsInQueue.containsKey(r)) {
         // This entry has no delay so it will be added at the top of the flush
@@ -464,15 +464,17 @@ class MemStoreFlusher implements FlushRequester {
         FlushRegionEntry fqe = new FlushRegionEntry(r, forceFlushAllStores, tracker);
         this.regionsInQueue.put(r, fqe);
         this.flushQueue.add(fqe);
+        r.incrementFlushesQueuedCount();
+        return true;
       } else {
         tracker.notExecuted("Flush already requested on " + r);
+        return false;
       }
     }
   }
 
   @Override
-  public void requestDelayedFlush(HRegion r, long delay, boolean forceFlushAllStores) {
+  public boolean requestDelayedFlush(HRegion r, long delay, boolean forceFlushAllStores) {
-    r.incrementFlushesQueuedCount();
     synchronized (regionsInQueue) {
       if (!regionsInQueue.containsKey(r)) {
         // This entry has some delay
@@ -481,7 +483,10 @@ class MemStoreFlusher implements FlushRequester {
         fqe.requeue(delay);
         this.regionsInQueue.put(r, fqe);
         this.flushQueue.add(fqe);
+        r.incrementFlushesQueuedCount();
+        return true;
       }
+      return false;
     }
   }
 

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestHeapMemoryManager.java

@@ -758,14 +758,15 @@ public class TestHeapMemoryManager {
     }
 
     @Override
-    public void requestFlush(HRegion region, boolean forceFlushAllStores,
+    public boolean requestFlush(HRegion region, boolean forceFlushAllStores,
         FlushLifeCycleTracker tracker) {
       this.listener.flushRequested(flushType, region);
+      return true;
     }
 
     @Override
-    public void requestDelayedFlush(HRegion region, long delay, boolean forceFlushAllStores) {
+    public boolean requestDelayedFlush(HRegion region, long delay, boolean forceFlushAllStores) {
-
+      return true;
     }
 
     @Override

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/AbstractTestWALReplay.java

@@ -1109,16 +1109,18 @@ public abstract class AbstractTestWALReplay {
     private HRegion r;
 
     @Override
-    public void requestFlush(HRegion region, boolean force, FlushLifeCycleTracker tracker) {
+    public boolean requestFlush(HRegion region, boolean force, FlushLifeCycleTracker tracker) {
       try {
         r.flush(force);
+        return true;
       } catch (IOException e) {
         throw new RuntimeException("Exception flushing", e);
       }
     }
 
     @Override
-    public void requestDelayedFlush(HRegion region, long when, boolean forceFlushAllStores) {
+    public boolean requestDelayedFlush(HRegion region, long when, boolean forceFlushAllStores) {
+      return true;
     }
 
     @Override