Flink ParquetSinkWriter FileAlreadyExistsException

Question

我正在尝试通过使用BucketingSink和自定义的ParquetSinkWriter在HDFS上使用Apache Flink编写Parquet文件。

这里是代码，上面的错误指示从下面开始启用检查点（在BucketingSink类中调用snapshotState（））刷新方法时无法正常工作。甚至writer也被“ writer.close（）;”关闭。但仍然收到来自“ writer = createWriter（）;”的错误。有什么想法吗？谢谢

类似这样的错误：

org.apache.hadoop.fs.FileAlreadyExistsException：/user/hive/flink_parquet_fils_with_checkingpoint/year=20/month=2/day=1/hour=17/_part-4-9.in-progress对于客户端192.168.56.202已经存在在org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInternal（FSNamesystem.java:3003）在org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInt（FSNamesystem.java:2890）

....。在flink.untils.ParquetSinkWriter.flush（ParquetSinkWriterForecast.java:81）在org.apache.flink.streaming.connectors.fs.bucketing.BucketingSink.snapshotState（BucketingSink.java:749）

import org.apache.flink.util.Preconditions;

import org.apache.avro.Schema;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericRecord;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.parquet.avro.AvroParquetWriter;
import org.apache.parquet.hadoop.ParquetWriter;
import org.apache.parquet.hadoop.metadata.CompressionCodecName;

import java.io.IOException;

/**
 * Parquet writer.
 *
 * @param <T>
 */
public class ParquetSinkWriter<T extends GenericRecord> implements Writer<T> {

    private static final long serialVersionUID = -975302556515811398L;

    private final CompressionCodecName compressionCodecName = CompressionCodecName.SNAPPY;
    private final int pageSize = 64 * 1024;

    private final String schemaRepresentation;

    private transient Schema schema;
    private transient ParquetWriter<GenericRecord> writer;
    private transient Path path;

    private int position;

    public ParquetSinkWriter(String schemaRepresentation) {
        this.schemaRepresentation = Preconditions.checkNotNull(schemaRepresentation);
    }

    @Override
    public void open(FileSystem fs, Path path) throws IOException {
        this.position = 0;
        this.path = path;

        if (writer != null) {
            writer.close();
        }

        writer = createWriter();
    }

    @Override
    public long flush() throws IOException {
        Preconditions.checkNotNull(writer);
        position += writer.getDataSize();
        writer.close();
        writer = createWriter();

        return position;
    }

    @Override
    public long getPos() throws IOException {
        Preconditions.checkNotNull(writer);
        return position + writer.getDataSize();
    }

    @Override
    public void close() throws IOException {
        if (writer != null) {
            writer.close();
            writer = null;
        }
    }

    @Override
    public void write(T element) throws IOException {
        Preconditions.checkNotNull(writer);
        writer.write(element);
    }

    @Override
    public Writer<T> duplicate() {
        return new ParquetSinkWriter<>(schemaRepresentation);
    }

    private ParquetWriter<GenericRecord> createWriter() throws IOException {
        if (schema == null) {
            schema = new Schema.Parser().parse(schemaRepresentation);
        }

        return AvroParquetWriter.<GenericRecord>builder(path)
            .withSchema(schema)
            .withDataModel(new GenericData())
            .withCompressionCodec(compressionCodecName)
            .withPageSize(pageSize)
            .build();
    }
}

Answer 1

似乎您正在尝试创建的文件当前存在。这是因为您使用的是默认写入模式CREATE，该模式在文件存在时会失败。您可以尝试将代码更改为使用OVERWRITE模式。您可以更改createWriter()方法以返回如下内容：

return AvroParquetWriter.<GenericRecord>builder(path)
            .withSchema(schema)
            .withDataModel(new GenericData())
            .withCompressionCodec(compressionCodecName)
            .withPageSize(pageSize)
            .withWriteMode(ParquetFileWriter.Mode.OVERWRITE)
            .build();