Flume-常见错误

Flume-常见错误

1 Closing file failed. Will retry again in 120 seconds.

1.1 报错现象和解决

详细报错信息如下：

09 Aug 2019 17:00:31,787 WARN  [SinkRunner-PollingRunner-DefaultSinkProcessor] (org.apache.flume.sink.hdfs.BucketWriter$CloseHandler.close:348)  - Closing file: hdfs://xxx/20190813/.aaa.lzo.tmp failed. Will retry again in 120 seconds.
java.io.IOException: Callable timed out after 300000 ms on file: hdfs://xxx/20190813/.aaa.lzo.tmp
        at org.apache.flume.sink.hdfs.BucketWriter.callWithTimeout(BucketWriter.java:741)
        at org.apache.flume.sink.hdfs.BucketWriter.access$1000(BucketWriter.java:60)
        at org.apache.flume.sink.hdfs.BucketWriter$CloseHandler.close(BucketWriter.java:345)
        at org.apache.flume.sink.hdfs.BucketWriter.doClose(BucketWriter.java:440)
        at org.apache.flume.sink.hdfs.BucketWriter.close(BucketWriter.java:426)
        at org.apache.flume.sink.hdfs.BucketWriter.close(BucketWriter.java:410)
        at org.apache.flume.sink.hdfs.BucketWriter.close(BucketWriter.java:312)
        at org.apache.flume.sink.hdfs.BucketWriter.append(BucketWriter.java:597)
        at org.apache.flume.sink.hdfs.HDFSEventSink.process(HDFSEventSink.java:412)
        at org.apache.flume.sink.DefaultSinkProcessor.process(DefaultSinkProcessor.java:67)
        at org.apache.flume.SinkRunner$PollingRunner.run(SinkRunner.java:145)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.concurrent.TimeoutException
        at java.util.concurrent.FutureTask.get(FutureTask.java:205)
        at org.apache.flume.sink.hdfs.BucketWriter.callWithTimeout(BucketWriter.java:734)
        ... 11 more
        
09 Aug 2019 17:00:31,787 WARN  [DataStreamer for file /xxx/20190813/.aaa.lzo.tmp block BP-3264412962-192.168.1.1-1476857514193:blk_1770743824_711658976] (org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.closeResponder:869)  - Caught exception
java.lang.InterruptedException
        at java.lang.Object.wait(Native Method)
        at java.lang.Thread.join(Thread.java:1252)
        at java.lang.Thread.join(Thread.java:1326)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.closeResponder(DFSOutputStream.java:867)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.closeInternal(DFSOutputStream.java:835)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:831)

09 Aug 2019 17:00:31,792 INFO  [hdfs-sink-2-call-runner-2] (org.apache.flume.sink.hdfs.BucketWriter$7.call:681)  - Renaming hdfs://xxx/20190813/.aaa.lzo.tmp to hdfs://xxx/20190813/aaa.lzo

09 Aug 2019 17:04:31,789 ERROR [hdfs-sink-2-call-runner-6] (org.apache.flume.sink.hdfs.AbstractHDFSWriter.hflushOrSync:269)  - Error while trying to hflushOrSync!
09 Aug 2019 17:04:31,789 WARN  [hdfs-sink-2-call-runner-6] (org.apache.hadoop.security.UserGroupInformation.doAs:1696)  - PriviledgedActionException as:tom (auth:PROXY) via tom (auth:SIMPLE) cause:java.nio.channels.ClosedChannelException
09 Aug 2019 17:02:31,788 WARN  [hdfs-sink-2-roll-timer-0] (org.apache.flume.sink.hdfs.BucketWriter$CloseHandler.close:348)  - Closing file: hdfs://xxx/20190813/.aaa.lzo.tmp failed. Will retry again in 120 seconds.
java.nio.channels.ClosedChannelException
        at org.apache.hadoop.hdfs.DFSOutputStream.checkClosed(DFSOutputStream.java:1866)
        at org.apache.hadoop.hdfs.DFSOutputStream.flushOrSync(DFSOutputStream.java:2277)
        at org.apache.hadoop.hdfs.DFSOutputStream.hflush(DFSOutputStream.java:2222)
        at org.apache.hadoop.fs.FSDataOutputStream.hflush(FSDataOutputStream.java:130)
        at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.flume.sink.hdfs.AbstractHDFSWriter.hflushOrSync(AbstractHDFSWriter.java:266)
        at org.apache.flume.sink.hdfs.HDFSCompressedDataStream.close(HDFSCompressedDataStream.java:153)
        at org.apache.flume.sink.hdfs.BucketWriter$3.call(BucketWriter.java:319)
        at org.apache.flume.sink.hdfs.BucketWriter$3.call(BucketWriter.java:316)
        at org.apache.flume.sink.hdfs.BucketWriter$8$1.run(BucketWriter.java:727)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:422)
        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1693)
        at org.apache.flume.auth.UGIExecutor.execute(UGIExecutor.java:46)
        at org.apache.flume.sink.hdfs.BucketWriter$8.call(BucketWriter.java:724)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

09 Aug 2019 17:04:31,789 ERROR [hdfs-sink-2-call-runner-6] (org.apache.flume.sink.hdfs.AbstractHDFSWriter.hflushOrSync:269)  - Error while trying to hflushOrSync!
09 Aug 2019 17:04:31,789 WARN  [hdfs-sink-2-call-runner-6] (org.apache.hadoop.security.UserGroupInformation.doAs:1696)  - PriviledgedActionException as:tom (auth:PROXY) via tom (auth:SIMPLE) cause:java.nio.channels.ClosedChannelException
09 Aug 2019 17:02:31,788 WARN  [hdfs-sink-2-roll-timer-0] (org.apache.flume.sink.hdfs.BucketWriter$CloseHandler.close:348)  - Closing file: hdfs://xxx/20190813/.aaa.lzo.tmp failed. Will retry again in 120 seconds.
java.nio.channels.ClosedChannelException

# 后面一直重复上述错误

我们发现Hive数据少了，然后查看flume.log报上述错误。

随后使用以下指令查看了HDFS文件状态：

hdfs fsck /xxx/20190813 -openforwrite | grep OPENFORWRITE |awk -F ' ' '{print $1}'

输出类似如下：

............/xxx/20190813/aaa.lzo 2091 bytes, 1 block(s), OPENFORWRITE: .......................................................................................

也就是说，文件.aaa.lzo.tmp已经成功被重命名为aaa.lzo，但状态是OPENFORWRITE，并未正常关闭。我们通过以下命令对该文件进行手动关闭:

hdfs debug recoverLease -path /xxx/20190813/aaa.lzo

随后该文件不再处于OPENFORWRITE状态，重新执行Hive查询，发现数据已经补足了。

1.2 原理分析

上图就是Flume HDFSSink RollInterval时的异常流程，可以发现虽然在HDFSWriter.close(.aaa.lzo.tmp)时发生了TimeoutException，进行了Cancel操作造成InterruptedException，并使用线程池进行文件close的重试。但是rename过程是依旧会继续执行的，因为上述放入close重试过程是通过submit()方法放入线程池异步执行的。
也就是说，文件名.aaa.lzo.tmp已经被修改为aaa.lzo，但一直在以旧的文件名.aaa.lzo.tmp重复close文件。

我写了一个模拟该错误的代码如下：

import com.google.common.util.concurrent.ThreadFactoryBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;

import static java.util.concurrent.TimeUnit.SECONDS;

/** * @Author: chengc * @Date: 2019-08-16 14:45 */
public class FlumeBucketWriterErrorSimulation {
    private static final Logger logger = LoggerFactory.getLogger(FlumeBucketWriterErrorSimulation.class);

    private static int rollTimerPoolSize = 20;
    private static ScheduledExecutorService timedRollerPool = Executors.newScheduledThreadPool(rollTimerPoolSize,
            new ThreadFactoryBuilder().setNameFormat("hdfs-sink-2-roll-timer-%d").build());

    private static volatile ScheduledFuture<Void> timedRollFuture ;

    public static void close(String fileName, boolean first){
        logger.info("start to close file:{}", fileName);
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        if(first){
            logger.warn("TimeoutException happened, will retry, file:{}", fileName);
        }else{
            logger.warn("ClosedChannelException happened, will retry, file:{}", fileName);
        }
        timedRollerPool.schedule(() -> {
            close(fileName, false);
            return null;
        }, 5, SECONDS);
    }

    /** * 按指定delay调度一次线程 */
    public static void doClose(String fileName){
        timedRollFuture = timedRollerPool.schedule(() -> {
            logger.info("doClose file:{}", fileName);

            close(fileName, true);

            if (timedRollFuture != null && !timedRollFuture.isDone()) {
                logger.info("timedRollFuture.cancel");
                // do not cancel myself if running!
                timedRollFuture.cancel(false);
                timedRollFuture = null;
            }

            String newName = "aaa.lzo";
            logger.info(" Renaming file:{} to {}", fileName, newName);
            return null;
        }, 5, SECONDS);
    }
    public static void main(String[] args) {
        doClose(".aaa.lzo.tmp");
    }
}

执行后部分输出如下：

2019-08-16 14:46:35.912 INFO  [hdfs-sink-2-roll-timer-0] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,50 - doClose file:.aaa.lzo.tmp
2019-08-16 14:46:35.915 INFO  [hdfs-sink-2-roll-timer-0] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,28 - start to close file:.aaa.lzo.tmp
2019-08-16 14:46:36.922 WARN  [hdfs-sink-2-roll-timer-0] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,35 - TimeoutException happened, will retry, file:.aaa.lzo.tmp
2019-08-16 14:46:36.923 INFO  [hdfs-sink-2-roll-timer-0] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,55 - timedRollFuture.cancel
2019-08-16 14:46:36.923 INFO  [hdfs-sink-2-roll-timer-0] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,62 -  Renaming file:.aaa.lzo.tmp to aaa.lzo
2019-08-16 14:46:41.927 INFO  [hdfs-sink-2-roll-timer-1] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,28 - start to close file:.aaa.lzo.tmp
2019-08-16 14:46:42.930 WARN  [hdfs-sink-2-roll-timer-1] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,37 - ClosedChannelException happened, will retry, file:.aaa.lzo.tmp
2019-08-16 14:46:47.936 INFO  [hdfs-sink-2-roll-timer-0] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,28 - start to close file:.aaa.lzo.tmp
2019-08-16 14:46:48.939 WARN  [hdfs-sink-2-roll-timer-0] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,37 - ClosedChannelException happened, will retry, file:.aaa.lzo.tmp
2019-08-16 14:46:53.942 INFO  [hdfs-sink-2-roll-timer-1] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,28 - start to close file:.aaa.lzo.tmp
2019-08-16 14:46:54.948 WARN  [hdfs-sink-2-roll-timer-1] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,37 - ClosedChannelException happened, will retry, file:.aaa.lzo.tmp
2019-08-16 14:46:59.950 INFO  [hdfs-sink-2-roll-timer-2] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,28 - start to close file:.aaa.lzo.tmp
2019-08-16 14:47:00.954 WARN  [hdfs-sink-2-roll-timer-2] concurrent.thread.executorservice.scheduled.FlumeBucketWriterErrorSimulation,37 - ClosedChannelException happened, will retry, file:.aaa.lzo.tmp

1.3 解决

本来想改源码，但需要快速解决，目前的方案就是改两个flume参数：

# 调用hdfs命令时超时时间，这里调大一倍
test.sinks.sink.hdfs.callTimeout=600000
# 关闭HDFS文件出错时重试次数，之前设为0即无限重试。现在改为20
test.sinks.sink.hdfs.closeTries=20

还搞了一个脚本，定期对目录下的文件手动close。

这是一个临时解决方案，未来需要改动源码，必须先close文件成功后再进行rename。