无法使用Spark从HDFS读取文件

Question

我已经使用cloudera管理器安装了cloudera CDH 5。

我可以轻松做到

hadoop fs -ls /input/war-and-peace.txt
hadoop fs -cat /input/war-and-peace.txt

上面的命令将在控制台上打印整个txt文件。

现在我启动火花壳并说

val textFile = sc.textFile("hdfs://input/war-and-peace.txt")
textFile.count

现在我得到一个错误

Spark上下文可用作sc。

scala> val textFile = sc.textFile("hdfs://input/war-and-peace.txt")
2014-12-14 15:14:57,874 INFO  [main] storage.MemoryStore (Logging.scala:logInfo(59)) - ensureFreeSpace(177621) called with curMem=0, maxMem=278302556
2014-12-14 15:14:57,877 INFO  [main] storage.MemoryStore (Logging.scala:logInfo(59)) - Block broadcast_0 stored as values in memory (estimated size 173.5 KB, free 265.2 MB)
textFile: org.apache.spark.rdd.RDD[String] = hdfs://input/war-and-peace.txt MappedRDD[1] at textFile at <console>:12

scala> textFile.count
2014-12-14 15:15:21,791 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 0 time(s); maxRetries=45
2014-12-14 15:15:41,905 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 1 time(s); maxRetries=45
2014-12-14 15:16:01,925 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 2 time(s); maxRetries=45
2014-12-14 15:16:21,983 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 3 time(s); maxRetries=45
2014-12-14 15:16:42,001 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 4 time(s); maxRetries=45
2014-12-14 15:17:02,062 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 5 time(s); maxRetries=45
2014-12-14 15:17:22,082 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 6 time(s); maxRetries=45
2014-12-14 15:17:42,116 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 7 time(s); maxRetries=45
2014-12-14 15:18:02,138 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 8 time(s); maxRetries=45
2014-12-14 15:18:22,298 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 9 time(s); maxRetries=45
2014-12-14 15:18:42,319 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 10 time(s); maxRetries=45
2014-12-14 15:19:02,354 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 11 time(s); maxRetries=45
2014-12-14 15:19:22,373 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 12 time(s); maxRetries=45
2014-12-14 15:19:42,424 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 13 time(s); maxRetries=45
2014-12-14 15:20:02,446 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 14 time(s); maxRetries=45
2014-12-14 15:20:22,512 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 15 time(s); maxRetries=45
2014-12-14 15:20:42,515 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 16 time(s); maxRetries=45
2014-12-14 15:21:02,550 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 17 time(s); maxRetries=45
2014-12-14 15:21:22,558 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 18 time(s); maxRetries=45
2014-12-14 15:21:42,683 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 19 time(s); maxRetries=45
2014-12-14 15:22:02,702 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 20 time(s); maxRetries=45
2014-12-14 15:22:22,832 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 21 time(s); maxRetries=45
2014-12-14 15:22:42,852 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 22 time(s); maxRetries=45
2014-12-14 15:23:02,974 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 23 time(s); maxRetries=45
2014-12-14 15:23:22,995 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 24 time(s); maxRetries=45
2014-12-14 15:23:43,109 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 25 time(s); maxRetries=45
2014-12-14 15:24:03,128 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 26 time(s); maxRetries=45
2014-12-14 15:24:23,250 INFO  [main] ipc.Client (Client.java:handleConnectionTimeout(814)) - Retrying connect to server: input/92.242.140.21:8020. Already tried 27 time(s); maxRetries=45
java.net.ConnectException: Call From dn1home/192.168.1.21 to input:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:783)
        at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:730)
        at org.apache.hadoop.ipc.Client.call(Client.java:1415)

为什么会出现此错误？ 我可以使用hadoop命令读取相同的文件吗？

Answer 1

这是解决方案

sc.textFile("hdfs://nn1home:8020/input/war-and-peace.txt")

我如何找到nn1home：8020？

只需搜索文件core-site.xml并查找xml元素fs.defaultFS

Answer 2

如果要使用sc.textFile("hdfs://...") ，则需要提供完整路径（绝对路径），在您的示例中为“ nn1home：8020 /。”。

如果要使其简单，则只需使用sc.textFile("hdfs:/input/war-and-peace.txt")

那只是一个/

Answer 3

这将起作用：

val textFile = sc.textFile("hdfs://localhost:9000/user/input.txt")

在这里，您可以从hadoop core-site.xml配置文件的fs.defaultFS参数值中获取localhost:9000 。

Answer 4

您没有传递正确的网址字符串。

• hdfs:// -协议类型
• localhost -IP地址（可能与您不同，例如-127.56.78.4）
• 54310端口号
• /input/war-and-peace.txt要加载的文件的完整路径。

最后，URL应该是这样的

hdfs://localhost:54310/input/war-and-peace.txt

Answer 5

我也在使用CDH5。 对我来说，完整的路径“ hdfs：// nn1home：8020”由于某种奇怪的原因而无法正常工作。 大多数示例显示了这样的路径。

我像这样使用命令

val textFile=sc.textFile("hdfs:/input1/Card_History2016_3rdFloor.csv")

以上命令的o / p：

textFile: org.apache.spark.rdd.RDD[String] = MapPartitionsRDD[1] at textFile at <console>:22

textFile.count

res1: Long = 58973  

这对我来说很好。

Answer 6

这对我有用

   logFile = "hdfs://localhost:9000/sampledata/sample.txt"

Answer 7

如果您在spark-env.sh中设置了HADOOP_HOME来启动spark，则spark将知道在哪里查找hdfs配置文件。

在这种情况下，spark已经知道您的namenode / datanode的位置，只有下面的名称才能正常访问hdfs文件；

sc.textFie("/myhdfsdirectory/myfiletoprocess.txt")

您可以如下创建myhdfs目录；

hdfs dfs -mkdir /myhdfsdirectory

从本地文件系统，您可以使用以下命令将myfiletoprocess.txt移至hdfs目录

hdfs dfs -copyFromLocal mylocalfile /myhdfsdirectory/myfiletoprocess.txt

Answer 8

 val conf = new SparkConf().setMaster("local[*]").setAppName("HDFSFileReader")
conf.set("fs.defaultFS", "hdfs://hostname:9000")
val sc = new SparkContext(conf)
val data = sc.textFile("hdfs://hostname:9000/hdfspath/")
data.saveAsTextFile("C:\\dummy\")

上面的代码从目录中读取所有hdfs文件，并将其本地保存在c：// dummy文件夹中。

Answer 9

也可能是文件路径或URL和hdfs端口问题。

解决方案：首先从$HADOOP_HOME/etc/hadoop位置打开core-site.xml文件，然后检查属性fs.defaultFS的值。 假设值是hdfs://localhost:9000并且hdfs中的文件位置是/home/usr/abc/fileName.txt 。 然后，文件URL将为： hdfs://localhost:9000/home/usr/abc/fileName.txt ，以下命令用于从hdfs读取文件：

var result= scontext.textFile("hdfs://localhost:9000/home/usr/abc/fileName.txt", 2)

Answer 10

从core-site.xml（/ etc / hadoop / conf）获取fs.defaultFS URL并按以下方式读取文件。 就我而言，fs.defaultFS是hdfs：//quickstart.cloudera：8020

txtfile = sc.textFile（'hdfs：//quickstart.cloudera：8020 / user / cloudera / rddoutput'）txtfile.collect（）