MapReduce报错：「MKDirs failed to create file」

0. 写在前面

• Linux：Ubuntu Kylin16.04
• Hadoop：Hadoop2.7.2

1. 程序代码及报错信息

输入、输出路径

zhangsan@hadoop01:/$ ll | grep input
drwxr-xr-x   3 zhangsan  zhangsan   4096 9月  20 03:35 input/
zhangsan@hadoop01:/$ ll | grep output
zhangsan@hadoop01:/$ 

程序代码

package com.mr.ch07.maxmin;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
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 MinMaxValueDemo7_2_1 {

	public static class MinMaxMapper extends Mapper<Object, Text, Text, MinMaxWritable> {

		private MinMaxWritable outTuple = new MinMaxWritable();

		@Override
		public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
			String[] strs = value.toString().split(" ");
			String strDate = strs[0];// 定义记录日期的字符串变量strDate

			if (strDate == null) {
				return;// 如果该日期值为空，则返回
			}

			System.out.println(strs[0] + ",,,," + strs[1]);

			// 将值即做为最大值又做为最小值存储到自定义Writable类MinMaxWritable中。
			outTuple.setMin(Integer.parseInt(strs[1]));
			outTuple.setMax(Integer.parseInt(strs[1]));
			
			// 将结果写入上下文
			context.write(new Text(strDate), outTuple);
		}

	}



	public static class MinMaxReducer extends Reducer<Text, MinMaxWritable, Text, MinMaxWritable> {

		private MinMaxWritable result = new MinMaxWritable();


		@Override
		public void reduce(Text key, Iterable<MinMaxWritable> values, Context context) 
			throws IOException, InterruptedException {
			
			result.setMax(0);
			result.setMin(0);

			// 按key迭代输出value的值
			for (MinMaxWritable val : values) {
				// 最小值放于结果集中
				if (result.getMin() == 0 || val.getMin() < result.getMin()) {
					result.setMin(val.getMin());
				}
				// 最大值放于结果集中
				if (result.getMax() == 0 || val.getMax() > result.getMax()) {
					System.out.println("val.getMax(): " + val.getMax() + ",,,,"
							+ result.getMax());
					result.setMax(val.getMax());
				}
			}
			context.write(key, result);
		}

	}

	public static void main(String[] args) throws Exception {

		Configuration conf = new Configuration();
		// String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
		String[] otherArgs = new String[] { "/input/ch07/minmax", "/output/ch07/minmax" };
		
		if (otherArgs.length != 2) {
			System.err.println("Usage: MinMaxCountDriver <in> <out>");
			System.exit(2);
		}

		// Job job = new Job(conf, "StackOverflow Comment Date Min Max Count");
		Job job = Job.getInstance(conf);
		job.setJarByClass(MinMaxValueDemo7_2_1.class);
		job.setMapperClass(MinMaxMapper.class);
		job.setCombinerClass(MinMaxReducer.class);
		job.setReducerClass(MinMaxReducer.class);


		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(MinMaxWritable.class);


		FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
		FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));


		System.exit(job.waitForCompletion(true) ? 0 : 1);
	}




	public static class MinMaxWritable implements Writable {
		private int min;// 记录最小值
		private int max;// 记录最大值

		public int getMin() {
			return min;
		}

		public void setMin(int min) {
			this.min = min;
		}

		public int getMax() {
			return max;
		}

		public void setMax(int max) {
			this.max = max;
		}



		@Override
		public void readFields(DataInput in) throws IOException {
			min = in.readInt();
			max = in.readInt();
		}



		@Override
		public void write(DataOutput out) throws IOException {
			out.writeInt(max);
				out.writeInt(min);
			}



		@Override
		public String toString() {
			return max + "\t" + min;
		}

	}

}

报错信息

java.lang.Exception: java.io.IOException: Mkdirs failed to create file:/output/ch07/minmax/_temporary/0/_temporary/attempt_local391816241_0001_r_000000_0 (exists=false, cwd=file:/home/zhangsan/Java_Eclipse/eclipse-workspace/MapReduce)
	at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
	at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:529)
Caused by: java.io.IOException: Mkdirs failed to create file:/output/ch07/minmax/_temporary/0/_temporary/attempt_local391816241_0001_r_000000_0 (exists=false, cwd=file:/home/zhangsan/Java_Eclipse/eclipse-workspace/MapReduce)
	at org.apache.hadoop.fs.ChecksumFileSystem.create(ChecksumFileSystem.java:449)
	at org.apache.hadoop.fs.ChecksumFileSystem.create(ChecksumFileSystem.java:435)
	at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:909)
	at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:890)
	at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:787)
	at org.apache.hadoop.mapreduce.lib.output.TextOutputFormat.getRecordWriter(TextOutputFormat.java:132)
	at org.apache.hadoop.mapred.ReduceTask$NewTrackingRecordWriter.<init>(ReduceTask.java:540)
	at org.apache.hadoop.mapred.ReduceTask.runNewReducer(ReduceTask.java:614)
	at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:389)
	at org.apache.hadoop.mapred.LocalJobRunner$Job$ReduceTaskRunnable.run(LocalJobRunner.java:319)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
2022-09-21 20:42:24,059 INFO  [main] mapreduce.Job (Job.java:monitorAndPrintJob(1360)) - Job job_local391816241_0001 running in uber mode : false
2022-09-21 20:42:24,062 INFO  [main] mapreduce.Job (Job.java:monitorAndPrintJob(1367)) -  map 100% reduce 0%
2022-09-21 20:42:24,064 INFO  [main] mapreduce.Job (Job.java:monitorAndPrintJob(1380)) - Job job_local391816241_0001 failed with state FAILED due to: NA
2022-09-21 20:42:24,080 INFO  [main] mapreduce.Job (Job.java:monitorAndPrintJob(1385)) - Counters: 30
	File System Counters
		FILE: Number of bytes read=247
		FILE: Number of bytes written=269461
		FILE: Number of read operations=0
		FILE: Number of large read operations=0
		FILE: Number of write operations=0
	Map-Reduce Framework
		Map input records=8
		Map output records=8
		Map output bytes=128
		Map output materialized bytes=60
		Input split bytes=97
		Combine input records=8
		Combine output records=3
		Reduce input groups=0
		Reduce shuffle bytes=60
		Reduce input records=0
		Reduce output records=0
		Spilled Records=3
		Shuffled Maps =1
		Failed Shuffles=0
		Merged Map outputs=1
		GC time elapsed (ms)=0
		Total committed heap usage (bytes)=193986560
	Shuffle Errors
		BAD_ID=0
		CONNECTION=0
		IO_ERROR=0
		WRONG_LENGTH=0
		WRONG_MAP=0
		WRONG_REDUCE=0
	File Input Format Counters 
		Bytes Read=96
	File Output Format Counters 
		Bytes Written=0

2. 查找资料

网上有一个帖子提到了这个报错信息

链接

https://community.cloudera.com/t5/Support-Questions/MKDirs-failed-to-create-file/td-p/35041

根据@snm1523的回答，我尝试将mapred-site.xml添加如下内容

<property>
    <name>mapreduce.jobtracker.address</name>
    <value>localhost:9101</value>
</property>

3. 原因分析

输出路径不能create，那就先创建输出路径

• 创建输出路径目录/output

zhangsan@hadoop01:/$ sudo mkdir /output
[sudo] zhangsan 的密码： 
zhangsan@hadoop01:/$ ll | grep output
drwxr-xr-x   2 root root  4096 9月  21 20:43 output/

依旧跟前面一样的报错信息

创建了路径还是报错，那应该是涉及到权限问题

• 修改/output目录权限为当前用户「即hadoop安装目录所在的所有者」

zhangsan@hadoop01:/$ sudo chown -R zhangsan:zhangsan output/
zhangsan@hadoop01:/$ ll | grep output
drwxr-xr-x   2 zhangsan  zhangsan   4096 9月  21 20:43 output/

重新执行MR程序

• 运行成功

2022-09-21 20:44:53,945 INFO  [Thread-15] mapred.LocalJobRunner (LocalJobRunner.java:runTasks(456)) - reduce task executor complete.
2022-09-21 20:44:54,597 INFO  [main] mapreduce.Job (Job.java:monitorAndPrintJob(1360)) - Job job_local2141955672_0001 running in uber mode : false
2022-09-21 20:44:54,600 INFO  [main] mapreduce.Job (Job.java:monitorAndPrintJob(1367)) -  map 100% reduce 100%
2022-09-21 20:44:54,602 INFO  [main] mapreduce.Job (Job.java:monitorAndPrintJob(1378)) - Job job_local2141955672_0001 completed successfully
2022-09-21 20:44:54,615 INFO  [main] mapreduce.Job (Job.java:monitorAndPrintJob(1385)) - Counters: 30
	File System Counters
		FILE: Number of bytes read=646
		FILE: Number of bytes written=541974
		FILE: Number of read operations=0
		FILE: Number of large read operations=0
		FILE: Number of write operations=0
	Map-Reduce Framework
		Map input records=8
		Map output records=8
		Map output bytes=128
		Map output materialized bytes=60
		Input split bytes=97
		Combine input records=8
		Combine output records=3
		Reduce input groups=3
		Reduce shuffle bytes=60
		Reduce input records=3
		Reduce output records=3
		Spilled Records=6
		Shuffled Maps =1
		Failed Shuffles=0
		Merged Map outputs=1
		GC time elapsed (ms)=0
		Total committed heap usage (bytes)=387973120
	Shuffle Errors
		BAD_ID=0
		CONNECTION=0
		IO_ERROR=0
		WRONG_LENGTH=0
		WRONG_MAP=0
		WRONG_REDUCE=0
	File Input Format Counters 
		Bytes Read=96
	File Output Format Counters 
		Bytes Written=60

• 查看结果

zhangsan@hadoop01:/output/ch07/minmax$ ll
总用量 20
drwxrwxr-x 2 zhangsan zhangsan 4096 9月  21 20:44 ./
drwxrwxr-x 3 zhangsan zhangsan 4096 9月  21 20:44 ../
-rw-r--r-- 1 zhangsan zhangsan   48 9月  21 20:44 part-r-00000
-rw-r--r-- 1 zhangsan zhangsan   12 9月  21 20:44 .part-r-00000.crc
-rw-r--r-- 1 zhangsan zhangsan    0 9月  21 20:44 _SUCCESS
-rw-r--r-- 1 zhangsan zhangsan    8 9月  21 20:44 ._SUCCESS.crc

4. 参考

https://community.cloudera.com/t5/Support-Questions/MKDirs-failed-to-create-file/td-p/35041

顺利结束