flume未解之谜

a1.sources = r1
a1.sinks = k1
a1.channels = c1

a1.sources.r1.type = exec
a1.sources.r1.command = tail -f /sinkslog/1.txt

a1.sinks.k1.type=hdfs
a1.sinks.k1.hdfs.path=hdfs://flume/log/%Y-%m-%j/%H:%M:%S
a1.sinks.k1.hdfs.filePrefix=FlumeDataPrefix-
a1.sinks.k1.hfds.batchSize=20
a1.sinks.k1.hdfs.round=true
a1.sinks.k1.hdfs.roundValue=10
a1.sinks.k1.hdfs.roundUnit=minute

a1.channels.c1.type=memory
a1.channels.c1.capacity=1000
a1.channels.c1.transactionCapacity=100

a1.sources.r1.channels=c1
a1.sinks.k1.channel=c1

此配置下报错：

java.lang.NullPointerException: Expected timestamp in the Flume event headers, but it was null
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:204)
at org.apache.flume.formatter.output.BucketPath.replaceShorthand(BucketPath.java:228)
at org.apache.flume.formatter.output.BucketPath.escapeString(BucketPath.java:432)
at org.apache.flume.sink.hdfs.HDFSEventSink.process(HDFSEventSink.java:380)
at org.apache.flume.sink.DefaultSinkProcessor.process(DefaultSinkProcessor.java:68)
at org.apache.flume.SinkRunner$PollingRunner.run(SinkRunner.java:147)
at java.lang.Thread.run(Thread.java:745)
18/08/09 17:01:55 ERROR flume.SinkRunner: Unable to deliver event. Exception follows.
org.apache.flume.EventDeliveryException: java.lang.NullPointerException: Expected timestamp in the Flume event headers, but it was null
at org.apache.flume.sink.hdfs.HDFSEventSink.process(HDFSEventSink.java:463)
at org.apache.flume.sink.DefaultSinkProcessor.process(DefaultSinkProcessor.java:68)
at org.apache.flume.SinkRunner$PollingRunner.run(SinkRunner.java:147)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException: Expected timestamp in the Flume event headers, but it was null
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:204)
at org.apache.flume.formatter.output.BucketPath.replaceShorthand(BucketPath.java:228)
at org.apache.flume.formatter.output.BucketPath.escapeString(BucketPath.java:432)
at org.apache.flume.sink.hdfs.HDFSEventSink.process(HDFSEventSink.java:380)
... 3 more