HBASE-22810 Initialize an separate ThreadPoolExecutor for taking/rest…

…oring snapshot (#486)

hbase-client/src/main/java/org/apache/hadoop/hbase/executor/EventType.java

@@ -203,13 +203,13 @@ public enum EventType {
    * C_M_SNAPSHOT_TABLE<br>
    * Client asking Master to snapshot an offline table.
    */
-  C_M_SNAPSHOT_TABLE        (48, ExecutorType.MASTER_TABLE_OPERATIONS),
+  C_M_SNAPSHOT_TABLE        (48, ExecutorType.MASTER_SNAPSHOT_OPERATIONS),
   /**
    * Messages originating from Client to Master.<br>
    * C_M_RESTORE_SNAPSHOT<br>
    * Client asking Master to restore a snapshot.
    */
-  C_M_RESTORE_SNAPSHOT      (49, ExecutorType.MASTER_TABLE_OPERATIONS),
+  C_M_RESTORE_SNAPSHOT      (49, ExecutorType.MASTER_SNAPSHOT_OPERATIONS),
 
   // Updates from master to ZK. This is done by the master and there is
   // nothing to process by either Master or RS

hbase-client/src/main/java/org/apache/hadoop/hbase/executor/ExecutorType.java

@@ -36,6 +36,7 @@ public enum ExecutorType {
   MASTER_RS_SHUTDOWN         (5),
   MASTER_META_SERVER_OPERATIONS (6),
   M_LOG_REPLAY_OPS           (7),
+  MASTER_SNAPSHOT_OPERATIONS (8),
 
   // RegionServer executor services
   RS_OPEN_REGION             (20),

hbase-common/src/main/java/org/apache/hadoop/hbase/HConstants.java

@@ -1258,6 +1258,33 @@ public static enum Modify {
   public static final String DEFAULT_TEMPORARY_HDFS_DIRECTORY = "/user/"
       + System.getProperty("user.name") + "/hbase-staging";
 
+  /**
+   * Configurations for master executor services.
+   */
+  public static final String MASTER_OPEN_REGION_THREADS =
+      "hbase.master.executor.openregion.threads";
+  public static final int MASTER_OPEN_REGION_THREADS_DEFAULT = 5;
+
+  public static final String MASTER_CLOSE_REGION_THREADS =
+      "hbase.master.executor.closeregion.threads";
+  public static final int MASTER_CLOSE_REGION_THREADS_DEFAULT = 5;
+
+  public static final String MASTER_SERVER_OPERATIONS_THREADS =
+      "hbase.master.executor.serverops.threads";
+  public static final int MASTER_SERVER_OPERATIONS_THREADS_DEFAULT = 5;
+
+  public static final String MASTER_META_SERVER_OPERATIONS_THREADS =
+      "hbase.master.executor.meta.serverops.threads";
+  public static final int MASTER_META_SERVER_OPERATIONS_THREADS_DEFAULT = 5;
+
+  public static final String MASTER_LOG_REPLAY_OPS_THREADS =
+      "hbase.master.executor.logreplayops.threads";
+  public static final int MASTER_LOG_REPLAY_OPS_THREADS_DEFAULT = 10;
+
+  public static final String MASTER_SNAPSHOT_OPERATIONS_THREADS =
+      "hbase.master.executor.snapshot.threads";
+  public static final int MASTER_SNAPSHOT_OPERATIONS_THREADS_DEFAULT = 3;
+
   private HConstants() {
     // Can't be instantiated with this ctor.
   }

hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java

@@ -1159,18 +1159,23 @@ public TableNamespaceManager getTableNamespaceManager() {
    *  as OOMEs; it should be lightly loaded. See what HRegionServer does if
    *  need to install an unexpected exception handler.
    */
-  private void startServiceThreads() throws IOException{
-   // Start the executor service pools
-   this.service.startExecutorService(ExecutorType.MASTER_OPEN_REGION,
-      conf.getInt("hbase.master.executor.openregion.threads", 5));
-   this.service.startExecutorService(ExecutorType.MASTER_CLOSE_REGION,
-      conf.getInt("hbase.master.executor.closeregion.threads", 5));
-   this.service.startExecutorService(ExecutorType.MASTER_SERVER_OPERATIONS,
-      conf.getInt("hbase.master.executor.serverops.threads", 5));
-   this.service.startExecutorService(ExecutorType.MASTER_META_SERVER_OPERATIONS,
-      conf.getInt("hbase.master.executor.serverops.threads", 5));
-   this.service.startExecutorService(ExecutorType.M_LOG_REPLAY_OPS,
-      conf.getInt("hbase.master.executor.logreplayops.threads", 10));
+  private void startServiceThreads() throws IOException {
+    // Start the executor service pools
+    this.service.startExecutorService(ExecutorType.MASTER_OPEN_REGION, conf.getInt(
+      HConstants.MASTER_OPEN_REGION_THREADS, HConstants.MASTER_OPEN_REGION_THREADS_DEFAULT));
+    this.service.startExecutorService(ExecutorType.MASTER_CLOSE_REGION, conf.getInt(
+      HConstants.MASTER_CLOSE_REGION_THREADS, HConstants.MASTER_CLOSE_REGION_THREADS_DEFAULT));
+    this.service.startExecutorService(ExecutorType.MASTER_SERVER_OPERATIONS,
+      conf.getInt(HConstants.MASTER_SERVER_OPERATIONS_THREADS,
+        HConstants.MASTER_SERVER_OPERATIONS_THREADS_DEFAULT));
+    this.service.startExecutorService(ExecutorType.MASTER_META_SERVER_OPERATIONS,
+      conf.getInt(HConstants.MASTER_META_SERVER_OPERATIONS_THREADS,
+        HConstants.MASTER_META_SERVER_OPERATIONS_THREADS_DEFAULT));
+    this.service.startExecutorService(ExecutorType.M_LOG_REPLAY_OPS, conf.getInt(
+      HConstants.MASTER_LOG_REPLAY_OPS_THREADS, HConstants.MASTER_LOG_REPLAY_OPS_THREADS_DEFAULT));
+    this.service.startExecutorService(ExecutorType.MASTER_SNAPSHOT_OPERATIONS,
+      conf.getInt(HConstants.MASTER_SNAPSHOT_OPERATIONS_THREADS,
+        HConstants.MASTER_SNAPSHOT_OPERATIONS_THREADS_DEFAULT));
 
    // We depend on there being only one instance of this executor running
    // at a time.  To do concurrency, would need fencing of enable/disable of

hbase-server/src/test/java/org/apache/hadoop/hbase/executor/TestExecutorService.java

@@ -21,6 +21,7 @@
 import static org.junit.Assert.*;
 import java.io.IOException;
 import java.io.StringWriter;
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -33,6 +34,7 @@
 import org.apache.hadoop.hbase.executor.ExecutorService.Executor;
 import org.apache.hadoop.hbase.executor.ExecutorService.ExecutorStatus;
 import org.apache.hadoop.hbase.testclassification.SmallTests;
+import org.junit.Assert;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
 
@@ -205,5 +207,39 @@ public boolean evaluate() throws Exception {
     executorService.shutdown();
   }
 
+  @Test
+  public void testSnapshotHandlers() throws Exception {
+    final Configuration conf = HBaseConfiguration.create();
+    final Server server = mock(Server.class);
+    when(server.getConfiguration()).thenReturn(conf);
+
+    final ExecutorService executorService = new ExecutorService("testSnapshotHandlers");
+    executorService.startExecutorService(ExecutorType.MASTER_SNAPSHOT_OPERATIONS, 1);
+
+    final CountDownLatch latch = new CountDownLatch(1);
+    executorService.submit(new EventHandler(server, EventType.C_M_SNAPSHOT_TABLE) {
+      @Override
+      public void process() throws IOException {
+        try {
+          latch.await();
+        } catch (InterruptedException e) {
+          Thread.currentThread().interrupt();
+        }
+      }
+    });
+
+    int activeCount = executorService.getExecutor(ExecutorType.MASTER_SNAPSHOT_OPERATIONS)
+        .getThreadPoolExecutor().getActiveCount();
+    Assert.assertEquals(activeCount, 1);
+    latch.countDown();
+    Waiter.waitFor(conf, 3000, new Predicate<Exception>() {
+      @Override
+      public boolean evaluate() throws Exception {
+        int count = executorService.getExecutor(ExecutorType.MASTER_SNAPSHOT_OPERATIONS)
+            .getThreadPoolExecutor().getActiveCount();
+        return count == 0;
+      }
+    });
+  }
 }