自定义水槽接收器：channel.takeEvent（）始终为null

Question

我需要一个水槽来为kudu写事件，所以我实现了自己的Kudu水槽。这是代码：

import java.util.Arrays;
import java.util.Map;
import org.apache.flume.Channel;
import org.apache.flume.Context;
import org.apache.flume.Event;
import org.apache.flume.EventDeliveryException;
import org.apache.flume.Transaction;
import org.apache.flume.conf.Configurable;
import org.apache.flume.sink.AbstractSink;
import org.kududb.client.Insert;
import org.kududb.client.KuduClient;
import org.kududb.client.KuduSession;
import org.kududb.client.KuduTable;
import org.kududb.client.PartialRow;
import org.kududb.client.SessionConfiguration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 *
 * @author cespedjo
 */
public class CustomKuduSink extends AbstractSink implements Configurable{

    private static final String KUDU_TABLE_COLUMNS_CSV = "kudu.columns";

    private static final String KUDU_MASTER_SERVER = "kudu.masterserver";

    private static final String KUDU_DATABASE = "kudu.database";

    private static final String KUDU_COLUMNS_TYPE_CSV = "kudu.columnstype";

    private static final String KUDU_EVT_HEADER_KEYS = "kudu.headerKeys";

    private static final String KUDU_MAX_EVENTS = "kudu.maxEvents";

    private String tableName;

    private String[] columns;

    private String kuduMaster;

    private String[] columnsTypes;

    private String[] evtheaderKeys;

    private KuduClient kuduClient;

    private KuduTable table;

    private int maxEvents;

    private static final Logger LOG = LoggerFactory
      .getLogger(CustomKuduSink.class);

    public static final String SESION_ID = "sesionId";
    public static final String PANTALLA = "pantalla";
    public static final String TYPE = "type";
    public static final String TIMESTAMP_CLIENTE = "timestampCliente";
    public static final String ENTIDAD = "entidad";
    public static final String ROW_KEY = "rowKey";
    public static final String TIMESTAMP = "timestamp";
    public static final String TARGET = "target";
    public static final String ACCION = "accion";
    public static final String IP = "ip";
    public static final String USERAGENT = "userAgent";
    public static final String TIMESTAMP_SERVIDOR = "timestampServidor";
    public static final String CONTENIDO_PAGINAORIGEN = "contenido$paginaOrigen";
    public static final String CONTENIDO_DURACION = "contenido$duracion";
    public static final String CONTENIDO_USERNAME = "contenido$username";
    public static final String CONTENIDO_USERTYPE = "contenido$usertype";
    public static final String CONTENIDO_LABEL = "contenido$label";
    public static final String CONTENIDO_VALUE = "contenido$value";

    @Override
    public Status process() throws EventDeliveryException {
        Status status = Status.READY;
        boolean readyForClose = false;

        Channel ch = getChannel();
        Transaction txn = ch.getTransaction();
        txn.begin();

        try {
            LOG.info("Taking event from channel... ");

            Event evt = ch.take();

            if (evt == null) {
                LOG.info("Event is null... ");
                //status = Status.BACKOFF;
            } else {
                LOG.info(evt.getHeaders().toString());

                Insert insert = table.newInsert();
                PartialRow row = insert.getRow();

                Map<String, String> headers = evt.getHeaders();
                KuduSession session = kuduClient.newSession(); 
                session.setFlushMode(SessionConfiguration.FlushMode.AUTO_FLUSH_SYNC);
                session.setTimeoutMillis(10000);

                for (int i = 0; i < this.columns.length; ++i) {
                    String aType = this.columnsTypes[i].trim();
                    String aColumn = this.columns[i].trim();
                    String value = headers.get(this.evtheaderKeys[i]);

                    LOG.info("column: " + aColumn + ",type: " + aType + ", value:" + value);
                    if (aType.equalsIgnoreCase("BIGINT"))
                        row.addLong(aColumn, value != null && !value.isEmpty() ?
                                Long.parseLong(value) :
                                -9999999999L);
                    if (aType.equalsIgnoreCase("STRING"))
                        row.addString(aColumn,
                                value == null || value.isEmpty() ? "NA" : value);
                    if (aType.equalsIgnoreCase("INT"))
                        row.addInt(aColumn, value != null && !value.isEmpty() ?
                                Integer.parseInt(value) :
                                -999999);
                    if (aType.equalsIgnoreCase("DECIMAL"))
                        row.addDouble(aColumn, value != null && !value.isEmpty() ?
                                Double.parseDouble(value) :
                                -99999.99);
                }

                session.apply(insert);

                LOG.info("Flushing... " + session.hasPendingOperations());
                session.close();
            }

            readyForClose = true;
            txn.commit();

        } catch (Throwable t) {
            LOG.error(t.getMessage());
            LOG.error(Arrays.toString(t.getStackTrace()));
            status = Status.BACKOFF;
            txn.rollback();
            readyForClose = true;

            if (t instanceof Error)
                throw (Error)t;
        } finally {
            if (readyForClose) {
                txn.close();
            } else {
                txn.rollback();
                txn.close();
            }
        }

        return status;
    }

    @Override
    public synchronized void start() {
        try {
            this.kuduClient = new KuduClient.KuduClientBuilder(this.kuduMaster)
                    .build();
            this.table = kuduClient.openTable(this.tableName);
        } catch (Exception ex) {
            LOG.error(Arrays.toString(ex.getStackTrace()));
        } finally {
            super.start();
        }
    }

    @Override
    public synchronized void stop() {
        super.stop();
        try {
            this.kuduClient.close();
            this.kuduClient.shutdown();
        } catch (Exception ex) {
            LOG.error(ex.getMessage());
            LOG.error(Arrays.toString(ex.getStackTrace()));
        }
    }



    @Override
    public void configure(Context context) {
        String columnsCsv = context.getString(KUDU_TABLE_COLUMNS_CSV);
        this.columns = columnsCsv.split(",");
        this.tableName = context.getString(KUDU_DATABASE);
        this.kuduMaster = context.getString(KUDU_MASTER_SERVER);
        String columnsTypesCsv = context.getString(KUDU_COLUMNS_TYPE_CSV);
        this.columnsTypes = columnsTypesCsv.split(",");
        String headerKeys = context.getString(KUDU_EVT_HEADER_KEYS);
        this.evtheaderKeys = headerKeys.split(",");
        this.maxEvents = context.getInteger(KUDU_MAX_EVENTS, 100);
    }

我有三个来源，三个内存通道和三个接收器。 HDFS和AsyncHbase接收器获取事件，但是这个定制的接收器无法捕获事件，即使源将事件注入每个通道。请帮忙。