[hbase] branch branch-2.3 updated: HBASE-25323 Fix potential NPE when the zookeeper path of RegionServerTracker does not exist when start (#2702)

[zghao]

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zghao pushed a commit to branch branch-2.3
in repository https://gitbox.apache.org/repos/asf/hbase.git


The following commit(s) were added to refs/heads/branch-2.3 by this push:
     new 6bf770c  HBASE-25323 Fix potential NPE when the zookeeper path of 
RegionServerTracker does not exist when start (#2702)
6bf770c is described below

commit 6bf770c1f403aec453cf73bccaf587bf7065462b
Author: Qi Yu <yuqi4...@gmail.com>
AuthorDate: Wed Nov 25 15:13:09 2020 +0800

    HBASE-25323 Fix potential NPE when the zookeeper path of 
RegionServerTracker does not exist when start (#2702)
    
    Signed-off-by: Duo Zhang <zhang...@apache.org>
    Signed-off-by: Guanghao Zhang <zg...@apache.org>
---
 .../hadoop/hbase/master/RegionServerTracker.java   | 28 +++++++++++++---------
 .../org/apache/hadoop/hbase/zookeeper/ZKUtil.java  |  5 ++--
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git 
a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/RegionServerTracker.java
 
b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/RegionServerTracker.java
index 9d33a21..336f9dc 100644
--- 
a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/RegionServerTracker.java
+++ 
b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/RegionServerTracker.java
@@ -19,6 +19,7 @@ package org.apache.hadoop.hbase.master;
 
 import java.io.IOException;
 import java.io.InterruptedIOException;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
@@ -35,6 +36,7 @@ import org.apache.hadoop.hbase.zookeeper.ZKListener;
 import org.apache.hadoop.hbase.zookeeper.ZKUtil;
 import org.apache.hadoop.hbase.zookeeper.ZKWatcher;
 import org.apache.hadoop.hbase.zookeeper.ZNodePaths;
+import 
org.apache.hbase.thirdparty.org.apache.commons.collections4.CollectionUtils;
 import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.zookeeper.KeeperException;
 import org.slf4j.Logger;
@@ -129,21 +131,24 @@ public class RegionServerTracker extends ZKListener {
     splittingServersFromWALDir.stream().filter(s -> 
!deadServersFromPE.contains(s)).
       forEach(s -> LOG.error("{} has no matching ServerCrashProcedure", s));
     //create ServerNode for all possible live servers from wal directory
-    liveServersFromWALDir.stream()
+    liveServersFromWALDir
         .forEach(sn -> 
server.getAssignmentManager().getRegionStates().getOrCreateServer(sn));
     watcher.registerListener(this);
     synchronized (this) {
       List<String> servers =
         ZKUtil.listChildrenAndWatchForNewChildren(watcher, 
watcher.getZNodePaths().rsZNode);
-      for (String n : servers) {
-        Pair<ServerName, RegionServerInfo> pair = getServerInfo(n);
-        ServerName serverName = pair.getFirst();
-        RegionServerInfo info = pair.getSecond();
-        regionServers.add(serverName);
-        ServerMetrics serverMetrics = info != null ? 
ServerMetricsBuilder.of(serverName,
-          VersionInfoUtil.getVersionNumber(info.getVersionInfo()),
-          info.getVersionInfo().getVersion()) : 
ServerMetricsBuilder.of(serverName);
-        serverManager.checkAndRecordNewServer(serverName, serverMetrics);
+      if (null != servers) {
+        for (String n : servers) {
+          Pair<ServerName, RegionServerInfo> pair = getServerInfo(n);
+          ServerName serverName = pair.getFirst();
+          RegionServerInfo info = pair.getSecond();
+          regionServers.add(serverName);
+          ServerMetrics serverMetrics = info != null ?
+            ServerMetricsBuilder.of(serverName, 
VersionInfoUtil.getVersionNumber(info.getVersionInfo()),
+              info.getVersionInfo().getVersion()) :
+            ServerMetricsBuilder.of(serverName);
+          serverManager.checkAndRecordNewServer(serverName, serverMetrics);
+        }
       }
       serverManager.findDeadServersAndProcess(deadServersFromPE, 
liveServersFromWALDir);
     }
@@ -163,8 +168,9 @@ public class RegionServerTracker extends ZKListener {
       server.abort("Unexpected zk exception getting RS nodes", e);
       return;
     }
-    Set<ServerName> servers =
+    Set<ServerName> servers = CollectionUtils.isEmpty(names) ? 
Collections.emptySet() :
       
names.stream().map(ServerName::parseServerName).collect(Collectors.toSet());
+
     for (Iterator<ServerName> iter = regionServers.iterator(); 
iter.hasNext();) {
       ServerName sn = iter.next();
       if (!servers.contains(sn)) {
diff --git 
a/hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKUtil.java 
b/hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKUtil.java
index 19d11d0..981265e 100644
--- 
a/hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKUtil.java
+++ 
b/hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKUtil.java
@@ -447,16 +447,15 @@ public final class ZKUtil {
     } catch(KeeperException.NoNodeException ke) {
       LOG.debug(zkw.prefix("Unable to list children of znode " + znode + " " +
           "because node does not exist (not an error)"));
-      return null;
     } catch (KeeperException e) {
       LOG.warn(zkw.prefix("Unable to list children of znode " + znode + " "), 
e);
       zkw.keeperException(e);
-      return null;
     } catch (InterruptedException e) {
       LOG.warn(zkw.prefix("Unable to list children of znode " + znode + " "), 
e);
       zkw.interruptedException(e);
-      return null;
     }
+
+    return null;
   }
 
   /**