HDFS-15920.Solve the problem that the value of SafeModeMonitor#RECHECK_INTERVAL can be configured. (#2831). Contributed by JiangHua Zhu.

Signed-off-by: Ayush Saxena <ayushsaxena@apache.org>

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java

@@ -207,6 +207,10 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
       "dfs.namenode.replqueue.threshold-pct";
   public static final String  DFS_NAMENODE_SAFEMODE_MIN_DATANODES_KEY = "dfs.namenode.safemode.min.datanodes";
   public static final int     DFS_NAMENODE_SAFEMODE_MIN_DATANODES_DEFAULT = 0;
+  public static final String  DFS_NAMENODE_SAFEMODE_RECHECK_INTERVAL_KEY =
+      "dfs.namenode.safemode.recheck.interval";
+  public static final long    DFS_NAMENODE_SAFEMODE_RECHECK_INTERVAL_DEFAULT =
+      1000;
   public static final String  DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY =
       HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY;
   public static final String  DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_DEFAULT =

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManagerSafeMode.java

@@ -109,7 +109,7 @@ class BlockManagerSafeMode {
   /** Timestamp of the safe mode initialized. */
   private long startTime;
   /** the safe mode monitor thread. */
-  private final Daemon smmthread = new Daemon(new SafeModeMonitor());
+  private final Daemon smmthread;
 
   /** time of the last status printout */
   private long lastStatusReport;
@@ -156,6 +156,7 @@ class BlockManagerSafeMode {
         MILLISECONDS);
 
     this.inRollBack = isInRollBackMode(NameNode.getStartupOption(conf));
+    this.smmthread = new Daemon(new SafeModeMonitor(conf));
 
     LOG.info("{} = {}", DFS_NAMENODE_SAFEMODE_THRESHOLD_PCT_KEY, threshold);
     LOG.info("{} = {}", DFS_NAMENODE_SAFEMODE_MIN_DATANODES_KEY,
@@ -638,9 +639,22 @@ class BlockManagerSafeMode {
    * Periodically check whether it is time to leave safe mode.
    * This thread starts when the threshold level is reached.
    */
-  private class SafeModeMonitor implements Runnable {
+  final private class SafeModeMonitor implements Runnable {
     /** Interval in msec for checking safe mode. */
-    private static final long RECHECK_INTERVAL = 1000;
+    private long recheckInterval;
+
+    private SafeModeMonitor(Configuration conf) {
+      recheckInterval = conf.getLong(
+          DFSConfigKeys.DFS_NAMENODE_SAFEMODE_RECHECK_INTERVAL_KEY,
+          DFSConfigKeys.DFS_NAMENODE_SAFEMODE_RECHECK_INTERVAL_DEFAULT);
+      if (recheckInterval < 1) {
+        LOG.warn("Invalid value for " +
+            DFSConfigKeys.DFS_NAMENODE_SAFEMODE_RECHECK_INTERVAL_DEFAULT +
+            ".Should be greater than 0, but is {}", recheckInterval);
+        recheckInterval = DFSConfigKeys.DFS_NAMENODE_SAFEMODE_RECHECK_INTERVAL_DEFAULT;
+      }
+      LOG.info("Using {} as SafeModeMonitor Interval", recheckInterval);
+    }
 
     @Override
     public void run() {
@@ -660,7 +674,7 @@ class BlockManagerSafeMode {
         }
 
         try {
-          Thread.sleep(RECHECK_INTERVAL);
+          Thread.sleep(recheckInterval);
         } catch (InterruptedException ignored) {
         }
       }

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -1011,6 +1011,14 @@
   </description>
 </property>
 
+<property>
+  <name>dfs.namenode.safemode.recheck.interval</name>
+  <value>1000</value>
+  <description>
+    Interval in msec for checking safe mode.
+  </description>
+</property>
+
 <property>
   <name>dfs.namenode.safemode.extension</name>
   <value>30000</value>

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManagerSafeMode.java

@@ -230,6 +230,18 @@ public class TestBlockManagerSafeMode {
     assertEquals(BMSafeModeStatus.OFF, getSafeModeStatus());
   }
 
+  @Test(timeout = 20000)
+  public void testCheckSafeMode9() throws Exception {
+    Configuration conf = new HdfsConfiguration();
+    conf.setLong(DFSConfigKeys.DFS_NAMENODE_SAFEMODE_RECHECK_INTERVAL_KEY, 3000);
+    GenericTestUtils.LogCapturer logs =
+        GenericTestUtils.LogCapturer.captureLogs(BlockManagerSafeMode.LOG);
+    BlockManagerSafeMode blockManagerSafeMode = new BlockManagerSafeMode(bm,
+        fsn, true, conf);
+    String content = logs.getOutput();
+    assertTrue(content.contains("Using 3000 as SafeModeMonitor Interval"));
+  }
+
   /**
    * Test that the block safe increases up to block threshold.
    *