HBASE-25643 The delayed FlushRegionEntry should be removed when we ne… (#3049)

Signed-off-by: AnoopSamJohn <anoopsamjohn@apache.org>
Signed-off-by: stack <stack@apache.org>

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

@@ -8380,6 +8380,10 @@ public class HRegion implements HeapSize, PropagatingConfigurationObserver, Regi
     flushesQueued.increment();
   }
 
+  protected void decrementFlushesQueuedCount() {
+    flushesQueued.decrement();
+  }
+
   /**
    * If a handler thread is eligible for interrupt, make it ineligible. Should be paired
    * with {{@link #enableInterrupts()}.

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

@@ -72,7 +72,7 @@ class MemStoreFlusher implements FlushRequester {
   // These two data members go together.  Any entry in the one must have
   // a corresponding entry in the other.
   private final BlockingQueue<FlushQueueEntry> flushQueue = new DelayQueue<>();
-  private final Map<Region, FlushRegionEntry> regionsInQueue = new HashMap<>();
+  protected final Map<Region, FlushRegionEntry> regionsInQueue = new HashMap<>();
   private AtomicBoolean wakeupPending = new AtomicBoolean();
 
   private final long threadWakeFrequency;
@@ -126,20 +126,22 @@ class MemStoreFlusher implements FlushRequester {
     this.blockingWaitTime = conf.getInt("hbase.hstore.blockingWaitTime",
       90000);
     int handlerCount = conf.getInt("hbase.hstore.flusher.count", 2);
-    if (handlerCount < 1) {
-      LOG.warn("hbase.hstore.flusher.count was configed to {} which is less than 1, corrected to 1",
-          handlerCount);
-      handlerCount = 1;
+    if (server != null) {
+      if (handlerCount < 1) {
+        LOG.warn("hbase.hstore.flusher.count was configed to {} which is less than 1, "
+            + "corrected to 1", handlerCount);
+        handlerCount = 1;
+      }
+      LOG.info("globalMemStoreLimit="
+          + TraditionalBinaryPrefix
+              .long2String(this.server.getRegionServerAccounting().getGlobalMemStoreLimit(), "", 1)
+          + ", globalMemStoreLimitLowMark="
+          + TraditionalBinaryPrefix.long2String(
+            this.server.getRegionServerAccounting().getGlobalMemStoreLimitLowMark(), "", 1)
+          + ", Offheap="
+          + (this.server.getRegionServerAccounting().isOffheap()));
     }
     this.flushHandlers = new FlushHandler[handlerCount];
-    LOG.info("globalMemStoreLimit="
-        + TraditionalBinaryPrefix
-            .long2String(this.server.getRegionServerAccounting().getGlobalMemStoreLimit(), "", 1)
-        + ", globalMemStoreLimitLowMark="
-        + TraditionalBinaryPrefix.long2String(
-          this.server.getRegionServerAccounting().getGlobalMemStoreLimitLowMark(), "", 1)
-        + ", Offheap="
-        + (this.server.getRegionServerAccounting().isOffheap()));
   }
 
   public LongAdder getUpdatesBlockedMsHighWater() {
@@ -462,18 +464,28 @@ class MemStoreFlusher implements FlushRequester {
   public boolean requestFlush(HRegion r, List<byte[]> families,
       FlushLifeCycleTracker tracker) {
     synchronized (regionsInQueue) {
-      if (!regionsInQueue.containsKey(r)) {
-        // This entry has no delay so it will be added at the top of the flush
-        // queue. It'll come out near immediately.
-        FlushRegionEntry fqe = new FlushRegionEntry(r, families, tracker);
-        this.regionsInQueue.put(r, fqe);
-        this.flushQueue.add(fqe);
-        r.incrementFlushesQueuedCount();
-        return true;
-      } else {
-        tracker.notExecuted("Flush already requested on " + r);
-        return false;
+      FlushRegionEntry existFqe = regionsInQueue.get(r);
+      if (existFqe != null) {
+        // if a delayed one exists and not reach the time to execute, just remove it
+        if (existFqe.isDelay() && existFqe.whenToExpire > EnvironmentEdgeManager.currentTime()) {
+          LOG.info("Remove the existing delayed flush entry for {}, "
+            + "because we need to flush it immediately", r);
+          this.regionsInQueue.remove(r);
+          this.flushQueue.remove(existFqe);
+          r.decrementFlushesQueuedCount();
+        } else {
+          tracker.notExecuted("Flush already requested on " + r);
+          return false;
+        }
       }
+
+      // This entry has no delay so it will be added at the top of the flush
+      // queue. It'll come out near immediately.
+      FlushRegionEntry fqe = new FlushRegionEntry(r, families, tracker);
+      this.regionsInQueue.put(r, fqe);
+      this.flushQueue.add(fqe);
+      r.incrementFlushesQueuedCount();
+      return true;
     }
   }
 
@@ -868,6 +880,13 @@ class MemStoreFlusher implements FlushRequester {
       return (EnvironmentEdgeManager.currentTime() - this.createTime) > maximumWait;
     }
 
+    /**
+     * @return True if the entry is a delay flush task
+     */
+    protected boolean isDelay() {
+      return this.whenToExpire > this.createTime;
+    }
+
     /**
      * @return Count of times {@link #requeue(long)} was called; i.e this is
      * number of times we've been requeued.

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

@@ -0,0 +1,98 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.regionserver;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HBaseClassTestRule;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.RegionInfo;
+import org.apache.hadoop.hbase.client.RegionInfoBuilder;
+import org.apache.hadoop.hbase.testclassification.RegionServerTests;
+import org.apache.hadoop.hbase.testclassification.SmallTests;
+import org.apache.hadoop.hbase.util.Threads;
+import org.junit.Before;
+import org.junit.ClassRule;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+import org.junit.rules.TestName;
+
+@Category({ RegionServerTests.class, SmallTests.class })
+public class TestMemStoreFlusher {
+
+  @ClassRule
+  public static final HBaseClassTestRule CLASS_RULE =
+      HBaseClassTestRule.forClass(TestMemStoreFlusher.class);
+
+  @Rule
+  public TestName name = new TestName();
+
+  public MemStoreFlusher msf;
+
+  @Before
+  public void setUp() throws Exception {
+    Configuration conf = new Configuration();
+    conf.set("hbase.hstore.flusher.count", "0");
+    msf = new MemStoreFlusher(conf, null);
+  }
+
+  @Test
+  public void testReplaceDelayedFlushEntry() {
+    RegionInfo hri =
+      RegionInfoBuilder.newBuilder(TableName.valueOf(name.getMethodName())).setRegionId(1)
+        .setReplicaId(0).build();
+    HRegion r = mock(HRegion.class);
+    doReturn(hri).when(r).getRegionInfo();
+
+    // put a delayed task with 30s delay
+    msf.requestDelayedFlush(r, 30000);
+    assertEquals(1, msf.getFlushQueueSize());
+    assertTrue(msf.regionsInQueue.get(r).isDelay());
+
+    // put a non-delayed task, then the delayed one should be replaced
+    assertTrue(msf.requestFlush(r, FlushLifeCycleTracker.DUMMY));
+    assertEquals(1, msf.getFlushQueueSize());
+    assertFalse(msf.regionsInQueue.get(r).isDelay());
+  }
+
+  @Test
+  public void testNotReplaceDelayedFlushEntryWhichExpired() {
+    RegionInfo hri =
+      RegionInfoBuilder.newBuilder(TableName.valueOf(name.getMethodName())).setRegionId(1)
+        .setReplicaId(0).build();
+    HRegion r = mock(HRegion.class);
+    doReturn(hri).when(r).getRegionInfo();
+
+    // put a delayed task with 100ms delay
+    msf.requestDelayedFlush(r, 100);
+    assertEquals(1, msf.getFlushQueueSize());
+    assertTrue(msf.regionsInQueue.get(r).isDelay());
+
+    Threads.sleep(200);
+
+    // put a non-delayed task, and the delayed one is expired, so it should not be replaced
+    assertFalse(msf.requestFlush(r, FlushLifeCycleTracker.DUMMY));
+    assertEquals(1, msf.getFlushQueueSize());
+    assertTrue(msf.regionsInQueue.get(r).isDelay());
+  }
+}