flume启动报错 java.lang.NoClassDefFoundError: org/htrace/Trace

我在启动Flume对hdfs写入时报如下错误:

ERROR [SinkRunner-PollingRunner-DefaultSinkProcessor] (org.apache.flume.sink.hdfs.HDFSEventSink.process:447)  - process failed
java.lang.NoClassDefFoundError: org/htrace/Trace
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:214)
        at com.sun.proxy.$Proxy12.create(Unknown Source)
        at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.create(ClientNamenodeProtocolTranslatorPB.java:295)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:187)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
        at com.sun.proxy.$Proxy13.create(Unknown Source)
        at org.apache.hadoop.hdfs.DFSOutputStream.newStreamForCreate(DFSOutputStream.java:1725)
        at org.apache.hadoop.hdfs.DFSClient.create(DFSClient.java:1668)
        at org.apache.hadoop.hdfs.DFSClient.create(DFSClient.java:1593)
        at org.apache.hadoop.hdfs.DistributedFileSystem$6.doCall(DistributedFileSystem.java:397)
        at org.apache.hadoop.hdfs.DistributedFileSystem$6.doCall(DistributedFileSystem.java:393)
        at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
        at org.apache.hadoop.hdfs.DistributedFileSystem.create(DistributedFileSystem.java:393)
        at org.apache.hadoop.hdfs.DistributedFileSystem.create(DistributedFileSystem.java:337)
        at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:908)
        at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:889)
        at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:786)
        at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:775)
        at org.apache.flume.sink.hdfs.HDFSDataStream.doOpen(HDFSDataStream.java:81)
        at org.apache.flume.sink.hdfs.HDFSDataStream.open(HDFSDataStream.java:108)
        at org.apache.flume.sink.hdfs.BucketWriter$1.call(BucketWriter.java:262)
        at org.apache.flume.sink.hdfs.BucketWriter$1.call(BucketWriter.java:252)
        at org.apache.flume.sink.hdfs.BucketWriter$9$1.run(BucketWriter.java:701)
        at org.apache.flume.auth.SimpleAuthenticator.execute(SimpleAuthenticator.java:50)
        at org.apache.flume.sink.hdfs.BucketWriter$9.call(BucketWriter.java:698)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: org.htrace.Trace
        at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        ... 33 more

该错误不但对于Flume,对于Hbase,Spark等需要对hdfs读写的都有可能报错.
首先需要检查lib包中是否包含如下文件.
commons-configuration-1.6.jar、
hadoop-auth-2.7.2.jar、
hadoop-common-2.7.2.jar、
hadoop-hdfs-2.7.2.jar、
commons-io-2.4.jar、
htrace-core-3.1.0-incubating.jar
如果存在还报错可能为版本问题htrace-core-3.1.0-incubating.jar
CDH中的classpath中引入的是/opt/cloudera/parcels/CDH/jars/htrace-core-3.0.4.jar，而这个版本的时候，htrace还是org.htrace，而3.1.0的时候已经贡献给Apache了，改叫org.apache.htrace了。
所以需要下载htrace-core-3.0.4.jar