HBASE-26977 HMaster's ShutdownHook does not take effect, if tablesOnMaster is false (#4397)

Signed-off-by: Yu Li <liyu@apache.org>

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

@@ -342,6 +342,8 @@ public class HRegionServer extends Thread
   // shutdown. Also set by call to stop when debugging or running unit tests
   // of HRegionServer in isolation.
   private volatile boolean stopped = false;
+  // Only for testing
+  private boolean isShutdownHookInstalled = false;
 
   // Go down hard. Used if file system becomes unavailable and also in
   // debugging and unit tests.
@@ -1023,6 +1025,7 @@ public class HRegionServer extends Thread
       return;
     }
     try {
+      installShutdownHook();
       // Do pre-registration initializations; zookeeper, lease threads, etc.
       preRegistrationInitialization();
     } catch (Throwable e) {
@@ -1031,7 +1034,6 @@ public class HRegionServer extends Thread
 
     try {
       if (!isStopped() && !isAborted()) {
-        ShutdownHook.install(conf, dataFs, this, Thread.currentThread());
         // Initialize the RegionServerCoprocessorHost now that our ephemeral
         // node was created, in case any coprocessors want to use ZooKeeper
         this.rsHost = new RegionServerCoprocessorHost(this, this.conf);
@@ -1254,6 +1256,22 @@ public class HRegionServer extends Thread
     LOG.info("Exiting; stopping=" + this.serverName + "; zookeeper connection closed.");
   }
 
+  /**
+   * This method is called when HMaster and HRegionServer are started.
+   * Please see to HBASE-26977 for details.
+   */
+  private void installShutdownHook() {
+    ShutdownHook.install(conf, dataFs, this, Thread.currentThread());
+    isShutdownHookInstalled = true;
+  }
+
+  /**
+   * This method is used for testing.
+   */
+  public boolean isShutdownHookInstalled() {
+    return isShutdownHookInstalled;
+  }
+
   private boolean containsMetaTableRegions() {
     return onlineRegions.containsKey(RegionInfoBuilder.FIRST_META_REGIONINFO.getEncodedName());
   }

hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestMaster.java

@@ -260,4 +260,10 @@ public class TestMaster {
     // Assert lock gets put in place again.
     assertTrue(fs.exists(hbckLockPath));
   }
+
+  @Test
+  public void testInstallShutdownHook() {
+    // Test for HBASE-26977
+    assertTrue(TEST_UTIL.getMiniHBaseCluster().getMaster().isShutdownHookInstalled());
+  }
 }

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

@@ -300,4 +300,10 @@ public class TestRegionServerNoMaster {
       openRegion(HTU, getRS(), hri);
     }
   }
+
+  @Test
+  public void testInstallShutdownHook() {
+    // Test for HBASE-26977
+    Assert.assertTrue(HTU.getMiniHBaseCluster().getRegionServer(0).isShutdownHookInstalled());
+  }
 }