一、问题描述
本地开发sparkSQL代码，连接hive，使用hivecontext连接报错：
（1）代码：
object _02hivecontext {
def main(args: Array[String]): Unit = {
//1)创建相关的context
val sparkconf=new SparkConf().setAppName("Hivesql").setMaster("local[2]")
val sc=SparkContext.getOrCreate(sparkconf)
val hiveContext=new HiveContext(sc)
//2)相关处理
hiveContext.table("emp").show()
//3）关闭资源
sc.stop()
}
}（2）报错：
19/01/18 07:36:57 INFO DFSClient: Could not obtain BP-397724921-127.0.0.1-1542712516755:blk_1073746318_5503 from any node: java.io.IOException: No live nodes contain current block. Will get new block locations from namenode and retry...
19/01/18 07:36:57 WARN DFSClient: DFS chooseDataNode: got # 1 IOException, will wait for 1090.0845058769598 msec.
19/01/18 07:37:19 WARN DFSClient: Failed to connect to /172.16.0.147:50010 for block, add to deadNodes and continue. java.net.ConnectException: Connection timed out: no further information
java.net.ConnectException: Connection timed out: no further information
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:529)
at org.apache.hadoop.hdfs.DFSInputStream.newTcpPeer(DFSInputStream.java:955)
at org.apache.hadoop.hdfs.DFSInputStream.getBlockReader(DFSInputStream.java:1107)
at org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:533)
at org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:749)
at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:793)
at java.io.DataInputStream.read(DataInputStream.java:100)
at org.apache.hadoop.util.LineReader.readDefaultLine(LineReader.java:211)
at org.apache.hadoop.util.LineReader.readLine(LineReader.java:174)
at org.apache.hadoop.mapred.LineRecordReader.next(LineRecordReader.java:206)
at org.apache.hadoop.mapred.LineRecordReader.next(LineRecordReader.java:45)
at org.apache.spark.rdd.HadoopRDD$$anon$1.getNext(HadoopRDD.scala:266)
at org.apache.spark.rdd.HadoopRDD$$anon$1.getNext(HadoopRDD.scala:211)
at org.apache.spark.util.NextIterator.hasNext(NextIterator.scala:73)
at org.apache.spark.InterruptibleIterator.hasNext(InterruptibleIterator.scala:39)
at scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:408)
at scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:408)
at scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:408)
at org.apache.spark.sql.execution.SparkPlan$$anonfun$2.apply(SparkPlan.scala:231)
at org.apache.spark.sql.execution.SparkPlan$$anonfun$2.apply(SparkPlan.scala:225)
at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$25.apply(RDD.scala:826)
at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$25.apply(RDD.scala:826)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
at org.apache.spark.scheduler.Task.run(Task.scala:99)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:282)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
19/01/18 07:37:19 INFO DFSClient: Could not obtain BP-397724921-127.0.0.1-1542712516755:blk_1073746318_5503 from any node: java.io.IOException: No live nodes contain current block. Will get new block locations from namenode and retry...
19/01/18 07:37:19 WARN DFSClient: DFS chooseDataNode: got # 2 IOException, will wait for 3919.861063005625 msec.
自己百思不得解，因为之前遇到过类似的问题，是把hive-site.xml放到main目录下的resources文件夹下即可。但是这个却解决不了，困扰了一个多星期！
二、问题原因
1.认为hdfs问题，但是查看50070主页，是没有问题的。
2.认为是datanode，但是看datanode日志，也没有问题，没有丢失块。
3.服务器本地hive-site.xml也放到了，spark的conf里面了。
4.怀疑sparkSQL有问题，但是，服务器打开SparkSQL却是可以访问hive的。
5.metastore也确认打开了。
本来已经绝望了，但是搜到类似报错可能是：外网无法访问hdfs文件系统，就尝试了一下，没想到竟然真的是这个问题。这个坑爹的问题。本质原因是：
本地机器和服务器不在一个局域网内，hadoop是使用内网ip作为机器相互通信。所以，在本地访问到namenode没有问题，因为配置了hosts，但是namenode会返回datanode的内网ip和端口，从而可以读写数据。关键这个返回内网ip我们在外网是访问不到的，所以会引起报错。
三、解决
在代码中设置dfs.client.use.datanode.hostname属性为true，从而使namenode返回给datanode的域名，从而可以访问datanode。解决代码如下：
object _02hivecontext {
def main(args: Array[String]): Unit = {
//1)创建相关的context
val sparkconf=new SparkConf().setAppName("Hivesql").setMaster("local[2]")
.set("dfs.client.use.datanode.hostname","true")
val sc=SparkContext.getOrCreate(sparkconf)
val hiveContext=new HiveContext(sc)
//2)相关处理
hiveContext.table("emp").show()
//3）关闭资源
sc.stop()
}
}服务器真的是踩坑日记。结果：
+-----+------+---------+----+----------+------+------+------+
|empno| ename| job| mgr| hiredate| sal| comm|deptno|
+-----+------+---------+----+----------+------+------+------+
| 7369| SMITH| CLERK|7902|1980-12-17| 800.0| null| 20|
| 7499| ALLEN| SALESMAN|7698| 1981-2-20|1600.0| 300.0| 30|
| 7521| WARD| SALESMAN|7698| 1981-2-22|1250.0| 500.0| 30|
| 7566| JONES| MANAGER|7839| 1981-4-2|2975.0| null| 20|
| 7654|MARTIN| SALESMAN|7698| 1981-9-28|1250.0|1400.0| 30|
| 7698| BLAKE| MANAGER|7839| 1981-5-1|2850.0| null| 30|
| 7782| CLARK| MANAGER|7839| 1981-6-9|2450.0| null| 10|
| 7788| SCOTT| ANALYST|7566| 1987-4-19|3000.0| null| 20|
| 7839| KING|PRESIDENT|null|1981-11-17|5000.0| null| 10|
| 7844|TURNER| SALESMAN|7698| 1981-9-8|1500.0| 0.0| 30|
| 7876| ADAMS| CLERK|7788| 1987-5-23|1100.0| null| 20|
| 7900| JAMES| CLERK|7698| 1981-12-3| 950.0| null| 30|
| 7902| FORD| ANALYST|7566| 1981-12-3|3000.0| null| 20|
| 7934|MILLER| CLERK|7782| 1982-1-23|1300.0| null| 10|
+-----+------+---------+----+----------+------+------+------+