为什么它在使用存储在HDFS中的文件时说“(没有这样的文件或目录)”？

Question

所以我在HDFS上有这个文件，但是显然HDFS找不到它，我也不知道为什么。

我的代码是：

public static Schema getSchema() throws IOException {
    InputStream is = new FileInputStream("hdfs:///schema.movies");
    String ps = new String(is.readAllBytes());
    MessageType mt = MessageTypeParser.parseMessageType(ps);
    return new AvroSchemaConverter().convert(mt);
}

在这里可以看到schema.movies文件：

​

​

我得到的错误是：

Connected.
Configuring core
 - Setting hadoop.proxyuser.hue.hosts=*
 - Setting fs.defaultFS=hdfs://namenode:9000
 - Setting hadoop.http.staticuser.user=root
 - Setting io.compression.codecs=org.apache.hadoop.io.compress.SnappyCodec
 - Setting hadoop.proxyuser.hue.groups=*
Configuring hdfs
 - Setting dfs.namenode.datanode.registration.ip-hostname-check=false
 - Setting dfs.webhdfs.enabled=true
 - Setting dfs.permissions.enabled=false
Configuring yarn
 - Setting yarn.timeline-service.enabled=true
 - Setting yarn.scheduler.capacity.root.default.maximum-allocation-vcores=4
 - Setting yarn.resourcemanager.system-metrics-publisher.enabled=true
 - Setting yarn.resourcemanager.store.class=org.apache.hadoop.yarn.server.resourcemanager.recovery.FileSystemRMStateStore
 - Setting yarn.nodemanager.disk-health-checker.max-disk-utilization-per-disk-percentage=98.5
 - Setting yarn.log.server.url=http://historyserver:8188/applicationhistory/logs/
 - Setting yarn.resourcemanager.fs.state-store.uri=/rmstate
 - Setting yarn.timeline-service.generic-application-history.enabled=true
 - Setting yarn.log-aggregation-enable=true
 - Setting yarn.resourcemanager.hostname=resourcemanager
 - Setting yarn.scheduler.capacity.root.default.maximum-allocation-mb=8192
 - Setting yarn.nodemanager.aux-services=mapreduce_shuffle
 - Setting yarn.resourcemanager.resource_tracker.address=resourcemanager:8031
 - Setting yarn.timeline-service.hostname=historyserver
 - Setting yarn.resourcemanager.scheduler.address=resourcemanager:8030
 - Setting yarn.resourcemanager.address=resourcemanager:8032
 - Setting mapred.map.output.compress.codec=org.apache.hadoop.io.compress.SnappyCodec
 - Setting yarn.nodemanager.remote-app-log-dir=/app-logs
 - Setting yarn.resourcemanager.scheduler.class=org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler
 - Setting mapreduce.map.output.compress=true
 - Setting yarn.nodemanager.resource.memory-mb=16384
 - Setting yarn.resourcemanager.recovery.enabled=true
 - Setting yarn.nodemanager.resource.cpu-vcores=8
Configuring httpfs
Configuring kms
Configuring mapred
 - Setting mapreduce.map.java.opts=-Xmx3072m
 - Setting mapreduce.reduce.java.opts=-Xmx6144m
 - Setting mapreduce.reduce.memory.mb=8192
 - Setting yarn.app.mapreduce.am.env=HADOOP_MAPRED_HOME=/opt/hadoop-3.2.1/
 - Setting mapreduce.map.memory.mb=4096
 - Setting mapred.child.java.opts=-Xmx4096m
 - Setting mapreduce.reduce.env=HADOOP_MAPRED_HOME=/opt/hadoop-3.2.1/
 - Setting mapreduce.framework.name=yarn
 - Setting mapreduce.map.env=HADOOP_MAPRED_HOME=/opt/hadoop-3.2.1/
Configuring for multihomed network
Exception in thread "main" java.io.FileNotFoundException: hdfs:/schema.movies (No such file or directory)
        at java.io.FileInputStream.open0(Native Method)
        at java.io.FileInputStream.open(FileInputStream.java:195)
        at java.io.FileInputStream.<init>(FileInputStream.java:138)
        at java.io.FileInputStream.<init>(FileInputStream.java:93)
        at GGCD_Alinea1.ToParquet.getSchema(ToParquet.java:33)
        at GGCD_Alinea1.ToParquet.main(ToParquet.java:214)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.hadoop.util.RunJar.run(RunJar.java:323)
        at org.apache.hadoop.util.RunJar.main(RunJar.java:236)
Disconnected from container.

正如您所看到的，它说它找不到schema.movies文件，但是您可以看到它在HDFS中已经存储。是因为它没有使用来自org.apache.hadoop.fs.Path？的路径类。因为当我使用下面的代码(使用readAllBytes()路径)运行一个程序时，它会找到我的数据文件，但是在getSchema()中，我需要使用方法，这就是为什么我不在那里使用Path的原因。

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

        long startTime = System.nanoTime();

        Job job1 = Job.getInstance(new Configuration(), "ToParquetAlinea1");
        job1.setJarByClass(ToParquet.class);

        //input
        job1.setInputFormatClass(TextInputFormat.class);
        MultipleInputs.addInputPath(job1,new Path("hdfs:///title.basics.tsv.gz"),
                TextInputFormat.class, ToParquetMapperLeft.class);

        MultipleInputs.addInputPath(job1,new Path("hdfs:///title.ratings.tsv.gz"),
                TextInputFormat.class, ToParquetMapperRight.class);

        job1.setReducerClass(JoinReducer.class);

        //output
        job1.setOutputKeyClass(Void.class);
        job1.setOutputValueClass(GenericRecord.class);
        job1.setOutputFormatClass(AvroParquetOutputFormat.class);
        AvroParquetOutputFormat.setSchema(job1, getSchema());
        FileOutputFormat.setOutputPath(job1,new Path("hdfs:///resultado_parquet"));

        job1.setMapOutputKeyClass(Text.class);
        job1.setMapOutputValueClass(Text.class);

        job1.waitForCompletion(true);

        long endTime = System.nanoTime();
        long duration = (endTime - startTime)/1000000; //miliseconds
        System.out.println("\n\nTIME: " + duration +"\n");
    }

为什么会这样呢？

Answer 1

工作的getSchema()方法是：

  public static Schema getSchema() throws IOException {

        FileSystem fs = FileSystem.get(new Configuration());
        FSDataInputStream s = fs.open(new Path("hdfs:///schema.movies"));
        byte[] buf = new byte[10000];

        s.read(buf);

        String ps = new String(buf);
        MessageType mt = MessageTypeParser.parseMessageType(ps);
        return new AvroSchemaConverter().convert(mt);
    }