本文主要是介绍解决Exception: org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z 等一系列问题,lja,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
解决Exception: org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z 等一系列问题,ljavalangstring
一.简介
Windows下的 Eclipse上调试Hadoop2代码,所以我们在windows下的Eclipse配置hadoop-eclipse-plugin-2.6.0.jar插件,并在运行Hadoop代码时出现了一系列的问题,搞了好几天终于能运行起代码。接下来我们来看看问题并怎么解决,提供给跟我同样遇到的问题作为参考。
Hadoop2的WordCount.java统计代码如下:
import java.io.IOException; import java.util.StringTokenizer;import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;public class WordCount {public static class TokenizerMapperextends Mapper<Object, Text, Text, IntWritable>{private final static IntWritable one = new IntWritable(1);private Text word = new Text();public void map(Object key, Text value, Context context) throws IOException, InterruptedException {StringTokenizer itr = new StringTokenizer(value.toString());while (itr.hasMoreTokens()) {word.set(itr.nextToken());context.write(word, one);}}}public static class IntSumReducerextends Reducer<Text,IntWritable,Text,IntWritable> {private IntWritable result = new IntWritable();public void reduce(Text key, Iterable<IntWritable> values,Context context) throws IOException, InterruptedException {int sum = 0;for (IntWritable val : values) {sum += val.get();}result.set(sum);context.write(key, result);}}public static void main(String[] args) throws Exception {Configuration conf = new Configuration();Job job = Job.getInstance(conf, "word count");job.setJarByClass(WordCount.class);job.setMapperClass(TokenizerMapper.class);job.setCombinerClass(IntSumReducer.class);job.setReducerClass(IntSumReducer.class);job.setOutputKeyClass(Text.class);job.setOutputValueClass(IntWritable.class);FileInputFormat.addInputPath(job, new Path(args[0]));FileOutputFormat.setOutputPath(job, new Path(args[1]));System.exit(job.waitForCompletion(true) ? 0 : 1);} }
我们hadoop-eclipse-plugin-2.6.0.jar放到Eclipse的plugins目录下,我们的Eclipse目录是F:\tool\eclipse-jee-juno-SR2\eclipse-jee-juno-SR2\plugins,重启一下Eclipse,然后,打开Window-->Preferens,可以看到Hadoop Map/Reduc选项,然后点击出现了An internal error occurredduring: "Map/Reduce location status updater".java.lang.NullPointerException,如图所示:
解决:
我们发现刚配置部署的Hadoop2还没创建输入和输出目录,先在hdfs上建个文件夹 。
#bin/hdfs dfs -mkdir –p /user/root/input
#bin/hdfs dfs -mkdir -p /user/root/output
我们在Eclipse的DFS Locations目录下看到我们这两个目录,如图所示:
问题二.Exception in thread "main" java.lang.NullPointerException atjava.lang.ProcessBuilder.start(Unknown Source)
运行Hadoop2的WordCount.java代码时出现了这样错误,
log4j:WARNPlease initialize the log4j system properly. log4j:WARN Seehttp://logging.apache.org/log4j/1.2/faq.html#noconfig for more info. Exception in thread "main" java.lang.NullPointerExceptionatjava.lang.ProcessBuilder.start(Unknown Source)atorg.apache.hadoop.util.Shell.runCommand(Shell.java:482)atorg.apache.hadoop.util.Shell.run(Shell.java:455)atorg.apache.hadoop.util.Shell$ShellCommandExecutor.execute(Shell.java:715)atorg.apache.hadoop.util.Shell.execCommand(Shell.java:808)atorg.apache.hadoop.util.Shell.execCommand(Shell.java:791)at
分析:
下载Hadoop2以上版本时,在Hadoop2的bin目录下没有winutils.exe
解决:
1.下载https://codeload.github.com/srccodes/hadoop-common-2.2.0-bin/zip/master下载hadoop-common-2.2.0-bin-master.zip,然后解压后,把hadoop-common-2.2.0-bin-master下的bin全部复制放到我们下载的Hadoop2的binHadoop2/bin目录下。如图所示:
2.Eclipse-》window-》Preferences 下的Hadoop Map/Peduce 把下载放在我们的磁盘的Hadoop目录引进来,如图所示:
3.Hadoop2配置变量环境HADOOP_HOME 和path,如图所示:
问题三.Exception in thread "main"java.lang.UnsatisfiedLinkError:org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z
当我们解决了问题三时,在运行WordCount.java代码时,出现这样的问题
log4j:WARN No appenders could be found forlogger (org.apache.hadoop.metrics2.lib.MutableMetricsFactory). log4j:WARN Please initialize the log4jsystem properly. log4j:WARN Seehttp://logging.apache.org/log4j/1.2/faq.html#noconfig for more info. Exception in thread "main"java.lang.UnsatisfiedLinkError:org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Zatorg.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Native Method)atorg.apache.hadoop.io.nativeio.NativeIO$Windows.access(NativeIO.java:557)atorg.apache.hadoop.fs.FileUtil.canRead(FileUtil.java:977)atorg.apache.hadoop.util.DiskChecker.checkAccessByFileMethods(DiskChecker.java:187)atorg.apache.hadoop.util.DiskChecker.checkDirAccess(DiskChecker.java:174)atorg.apache.hadoop.util.DiskChecker.checkDir(DiskChecker.java:108)atorg.apache.hadoop.fs.LocalDirAllocator$AllocatorPerContext.confChanged(LocalDirAllocator.java:285)atorg.apache.hadoop.fs.LocalDirAllocator$AllocatorPerContext.getLocalPathForWrite(LocalDirAllocator.java:344)atorg.apache.hadoop.fs.LocalDirAllocator.getLocalPathForWrite(LocalDirAllocator.java:150)atorg.apache.hadoop.fs.LocalDirAllocator.getLocalPathForWrite(LocalDirAllocator.java:131)atorg.apache.hadoop.fs.LocalDirAllocator.getLocalPathForWrite(LocalDirAllocator.java:115)atorg.apache.hadoop.mapred.LocalDistributedCacheManager.setup(LocalDistributedCacheManager.java:131)
分析:
C:\Windows\System32下缺少hadoop.dll,把这个文件拷贝到C:\Windows\System32下面即可。
解决:
hadoop-common-2.2.0-bin-master下的bin的hadoop.dll放到C:\Windows\System32下,然后重启电脑,也许还没那么简单,还是出现这样的问题。
我们在继续分析:
我们在出现错误的的atorg.apache.hadoop.io.nativeio.NativeIO$Windows.access(NativeIO.java:557)我们来看这个类NativeIO的557行,如图所示:
Windows的唯一方法用于检查当前进程的请求,在给定的路径的访问权限,所以我们先给以能进行访问,我们自己先修改源代码,return true 时允许访问。我们下载对应hadoop源代码,hadoop-2.6.0-src.tar.gz解压,hadoop-2.6.0-src\hadoop-common-project\hadoop-common\src\main\java\org\apache\hadoop\io\nativeio下NativeIO.java 复制到对应的Eclipse的project,然后修改557行为return true如图所示:
问题四:org.apache.hadoop.security.AccessControlException: Permissiondenied: user=zhengcy, access=WRITE,inode="/user/root/output":root:supergroup:drwxr-xr-x
我们在执行运行WordCount.java代码时,出现这样的问题
2014-12-18 16:03:24,092 WARN (org.apache.hadoop.mapred.LocalJobRunner:560) - job_local374172562_0001 org.apache.hadoop.security.AccessControlException: Permission denied: user=zhengcy, access=WRITE, inode="/user/root/output":root:supergroup:drwxr-xr-xat org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkFsPermission(FSPermissionChecker.java:271)at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:257)at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:238)at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkPermission(FSPermissionChecker.java:179)at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:6512)at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:6494)at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkAncestorAccess(FSNamesystem.java:6446)at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsInternal(FSNamesystem.java:4248)at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsInt(FSNamesystem.java:4218)at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirs(FSNamesystem.java:4191)at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.mkdirs(NameNodeRpcServer.java:813)
分析:
我们没权限访问output目录。
解决:
我们 在设置hdfs配置的目录是在hdfs-site.xml配置hdfs文件存放的地方,我在hadoop伪分布式部署那边有介绍过,我们在这边在复习一下,如图所示:
我们在这个etc/hadoop下的hdfs-site.xml添加
<property>
<name>dfs.permissions</name>
<value>false</value>
</property>
设置没有权限,不过我们在正式的 服务器上不能这样设置。
问题五:File/usr/root/input/file01._COPYING_ could only be replicated to 0 nodes instead ofminRepLication (=1) There are 0 datanode(s) running and no node(s) are excludedin this operation
如图所示:
分析:
我们在第一次执行#hadoop namenode –format 完然后在执行#sbin/start-all.sh
在执行#jps,能看到Datanode,在执行#hadoop namenode –format然后执行#jps这时看不到Datanode ,如图所示:
然后我们想把文本放到输入目录执行bin/hdfs dfs -put/usr/local/hadoop/hadoop-2.6.0/test/* /user/root/input 把/test/*文件上传到hdfs的/user/root/input中,出现这样的问题,
解决:
是我们执行太多次了hadoopnamenode –format,在创建了多个,我们对应的hdfs目录删除hdfs-site.xml配置的保存datanode和namenode目录。
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