Question

我是Avro Format的新手。我正在尝试使用Storm-Jms spout从JMS队列收集Avro消息，并使用hdfs bolt将它们发送到hdfs。

队列正在发送avro，但我无法使用HDFS BOLT以avro格式获取它们。

如何正确收集avro消息并将其发送到下游而不会在hdfs中编码错误。

Answer 1

现有的HDFS Bolt不支持编写avro文件，我们需要通过进行以下更改来克服这个问题。在此示例代码中，我使用从我的spout获取JMS消息并将这些JMS字节消息转换为AVRO并将它们发送到HDFS。

此代码可用作修改AbstractHdfsBolt中方法的示例。

public void execute(Tuple tuple) {          
        try {               
            long length = bytesMessage.getBodyLength();
            byte[] bytes = new byte[(int)length];
            ///////////////////////////////////////
            bytesMessage.readBytes(bytes);
            String replyMessage = new String(bytes, "UTF-8");

            datumReader = new SpecificDatumReader<IndexedRecord>(schema);
            decoder = DecoderFactory.get().binaryDecoder(bytes, null);

            result = datumReader.read(null, decoder);                               
            synchronized (this.writeLock) {                 
                dataFileWriter.append(result);                                      
                dataFileWriter.sync();
                this.offset += bytes.length;                    
               if (this.syncPolicy.mark(tuple, this.offset)) {
                   if (this.out instanceof HdfsDataOutputStream) {
                        ((HdfsDataOutputStream) this.out).hsync(EnumSet.of(SyncFlag.UPDATE_LENGTH));
                    } else {
                        this.out.hsync();
                        this.out.flush();
                    }
                    this.syncPolicy.reset();
                }
               dataFileWriter.flush();
            }

            if(this.rotationPolicy.mark(tuple, this.offset)){
                rotateOutputFile(); // synchronized
                this.offset = 0;
                this.rotationPolicy.reset();
            }
        } catch (IOException | JMSException e) {
            LOG.warn("write/sync failed.", e);
            this.collector.fail(tuple);
        } 
    }

@Override
void closeOutputFile() throws IOException {
    this.out.close();
}

@Override
Path createOutputFile() throws IOException {
    Path path = new Path(this.fileNameFormat.getPath(), this.fileNameFormat.getName(this.rotation, System.currentTimeMillis()));
    this.out = this.fs.create(path);
    dataFileWriter.create(schema, out);
    return path;
}

@Override
void doPrepare(Map conf, TopologyContext topologyContext,OutputCollector collector) throws IOException {
    // TODO Auto-generated method stub
     LOG.info("Preparing HDFS Bolt...");
     try {

            schema = new Schema.Parser().parse(new File("/home/*******/********SchemafileName.avsc"));
        } catch (IOException e1) {              
            e1.printStackTrace();
        }
     this.fs = FileSystem.get(URI.create(this.fsUrl), hdfsConfig);
     datumWriter = new SpecificDatumWriter<IndexedRecord>(schema);
     dataFileWriter = new DataFileWriter<IndexedRecord>(datumWriter);
     JMSAvroUtils JASV = new JMSAvroUtils();         
}

Storm-jms Spout收集Avro消息并向下传输？

1 个答案: