HBASE-1960 Master should wait for DFS to come up when creating hbase.version; use alternate strategy for waiting for DNs

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1079501 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -60,6 +60,8 @@ Release 0.91.0 - Unreleased
    HBASE-3605  Fix balancer log message
    HBASE-3603  Remove -XX:+HeapDumpOnOutOfMemoryError autodump of heap option
                on OOME
+   HBASE-1960  Master should wait for DFS to come up when creating
+               hbase.version; use alternate strategy for waiting for DNs
 
   IMPROVEMENTS
    HBASE-3290  Max Compaction Size (Nicolas Spiegelberg via Stack)  

src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java

@@ -231,7 +231,15 @@ public class MasterFileSystem {
     // Filesystem is good. Go ahead and check for hbase.rootdir.
     if (!fs.exists(rd)) {
       fs.mkdirs(rd);
-      FSUtils.setVersion(fs, rd);
+      // DFS leaves safe mode with 0 DNs when there are 0 blocks.
+      // We used to handle this by checking the current DN count and waiting until
+      // it is nonzero. With security, the check for datanode count doesn't work --
+      // it is a privileged op. So instead we adopt the strategy of the jobtracker
+      // and simply retry file creation during bootstrap indefinitely. As soon as
+      // there is one datanode it will succeed. Permission problems should have
+      // already been caught by mkdirs above.
+      FSUtils.setVersion(fs, rd, c.getInt(HConstants.THREAD_WAKE_FREQUENCY,
+        10 * 1000));
     } else {
       FSUtils.checkVersion(fs, rd, true);
     }

src/main/java/org/apache/hadoop/hbase/util/FSUtils.java

@@ -38,6 +38,7 @@ import org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException;
 import org.apache.hadoop.hdfs.protocol.FSConstants;
 import org.apache.hadoop.hdfs.server.namenode.LeaseExpiredException;
 import org.apache.hadoop.io.SequenceFile;
+import org.apache.hadoop.util.StringUtils;
 
 import java.io.DataInputStream;
 import java.io.EOFException;
@@ -207,7 +208,20 @@ public class FSUtils {
    */
   public static void setVersion(FileSystem fs, Path rootdir)
   throws IOException {
-    setVersion(fs, rootdir, HConstants.FILE_SYSTEM_VERSION);
+    setVersion(fs, rootdir, HConstants.FILE_SYSTEM_VERSION, 0);
+  }
+
+  /**
+   * Sets version of file system
+   *
+   * @param fs filesystem object
+   * @param rootdir hbase root
+   * @param wait time to wait for retry
+   * @throws IOException e
+   */
+  public static void setVersion(FileSystem fs, Path rootdir, int wait)
+  throws IOException {
+    setVersion(fs, rootdir, HConstants.FILE_SYSTEM_VERSION, wait);
   }
 
   /**
@@ -216,15 +230,33 @@ public class FSUtils {
    * @param fs filesystem object
    * @param rootdir hbase root directory
    * @param version version to set
+   * @param wait time to wait for retry
    * @throws IOException e
    */
-  public static void setVersion(FileSystem fs, Path rootdir, String version)
+  public static void setVersion(FileSystem fs, Path rootdir, String version,
-  throws IOException {
+      int wait) throws IOException {
+    while (true) try {
       FSDataOutputStream s =
         fs.create(new Path(rootdir, HConstants.VERSION_FILE_NAME));
       s.writeUTF(version);
       s.close();
-    LOG.debug("Created version file at " + rootdir.toString() + " set its version at:" + version);
+      LOG.debug("Created version file at " + rootdir.toString() +
+        " set its version at:" + version);
+      return;
+    } catch (IOException e) {
+      if (wait > 0) {
+        LOG.warn("Unable to create version file at " + rootdir.toString() +
+          ", retrying: " + StringUtils.stringifyException(e));
+        try {
+          Thread.sleep(wait);
+        } catch (InterruptedException ex) {
+          // ignore
+        }
+      } else {
+        // rethrow
+        throw e;
+      }
+    }
   }
 
   /**
@@ -262,22 +294,6 @@ public class FSUtils {
     FileSystem fs = FileSystem.get(conf);
     if (!(fs instanceof DistributedFileSystem)) return;
     DistributedFileSystem dfs = (DistributedFileSystem)fs;
-    // Are there any data nodes up yet?
-    // Currently the safe mode check falls through if the namenode is up but no
-    // datanodes have reported in yet.
-    try {
-      while (dfs.getDataNodeStats().length == 0) {
-        LOG.info("Waiting for dfs to come up...");
-        try {
-          Thread.sleep(wait);
-        } catch (InterruptedException e) {
-          //continue
-        }
-      }
-    } catch (IOException e) {
-      // getDataNodeStats can fail if superuser privilege is required to run
-      // the datanode report, just ignore it
-    }
     // Make sure dfs is not in safe mode
     while (dfs.setSafeMode(FSConstants.SafeModeAction.SAFEMODE_GET)) {
       LOG.info("Waiting for dfs to exit safe mode...");