Hadoop的NullWritable
Posted akia开凯
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了Hadoop的NullWritable相关的知识，希望对你有一定的参考价值。
1. Hadoop中的NullWritable
NullWritable是Writable的一个特殊类，实现方法为空实现，不从数据流中读数据，也不写入数据，只充当占位符，如在MapReduce中，如果你不需要使用键或值，你就可以将键或值声明为NullWritable,NullWritable是一个不可变的单实例类型。
比如，我设置map的输出为，这样做：
1 @Override 2 protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { 3 String line = value.toString(); 4 WebLogBean webLogBean = WebLogParser.parser(line); 5 WebLogParser.filtStaticResource(webLogBean, pages); // 过滤js/图片/css等静态资源 6 k.set(webLogBean.toString()); 7 context.write(k, NullWritable.get();); 8 }
不能使用new NullWritable()来定义，获取空值只能NullWritable.get()来获取
来自https://www.cnblogs.com/Skyar/p/5815486.html
2. Yarn上的各种Id
- jobId
描述：出自MapReduce，对作业的唯一标识。
格式：job_${clusterStartTime}_${jobid}
例子：job_1498552288473_2742
- applicationId
描述：在yarn中对作业的唯一标识。
格式：application_${clusterStartTime}_${applicationId}
例子：application_1498552288473_2742
- taskId
描述：作业中的任务的唯一标识
格式：task_${clusterStartTime}_${applicationId}_[m|r]_${taskId}
例子：task_1498552288473_2742_m_000000、task_1498552288473_2742_r_000000
- attempId
描述：任务尝试执行的一次id
格式：attempt_${clusterStartTime}_${applicationId}_[m|r]_${taskId}_${attempId}
例子：attempt_1498552288473_2742_m_000000_0
- appAttempId
描述：ApplicationMaster的尝试执行的一次id。
格式：appattempt_${clusterStartTime}_${applicationId}_${appAttempId}
例子：appattempt_1498552288473_2742_000001
- containerId
描述：container的id
格式：container_e*epoch*_${clusterStartTime}_${applicationId}_${appAttempId}_${containerId}
例子：container_e20_1498552288473_2742_01_000032、container_1498552288473_2742_01_000032参考：Yarn之日志分析
3. Yarn的运行日志存放目录以及备份目录
Yarn上任务的运行日志存在哪呢？你有没有疑问过，今天终于明白了，以Flink on yarn上的任务为例(其他任务类似，不一定完全相同)，看JobManager.log的截图
1 2019-08-05 09:51:55,826 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - -------------------------------------------------------------------------------- 2 2019-08-05 09:51:55,827 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - Starting YarnSessionClusterEntrypoint (Version: 1.7.1, Rev:<unknown>, Date:<unknown>) 3 2019-08-05 09:51:55,827 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - OS current user: yarn 4 2019-08-05 09:51:56,255 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - Current Hadoop/Kerberos user: worker 5 2019-08-05 09:51:56,255 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - JVM: Java HotSpot(TM) 64-Bit Server VM - Oracle Corporation - 1.8/25.65-b01 6 2019-08-05 09:51:56,255 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - Maximum heap size: 1388 MiBytes 7 2019-08-05 09:51:56,255 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - JAVA_HOME: /usr/local/jdk/ 8 2019-08-05 09:51:56,258 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - Hadoop version: 2.6.0-cdh5.5.0 9 2019-08-05 09:51:56,258 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - JVM Options: 10 2019-08-05 09:51:56,258 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - -Xmx1448m 11 2019-08-05 09:51:56,258 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - -Dlog.file=/var/log/hadoop/container/application_1564969910131_0252/container_e05_1564969910131_0252_01_000001/jobmanager.log 12 2019-08-05 09:51:56,258 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - -Dlogback.configurationFile=file:logback.xml 13 2019-08-05 09:51:56,258 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - -Dlog4j.configuration=file:log4j.properties 14 2019-08-05 09:51:56,258 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - Program Arguments: (none) 15 2019-08-05 09:51:56,259 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - Classpath: lib/flink-python_2.11-1.7.1.jar:lib/flink-shaded-hadoop2-uber-1.7.1.jar:lib/log4j-1.2.17.jar:lib/slf4j-log4j12-1.7.15.jar:log4j.properties:logback.xml:flink.jar:flink-conf.yaml::/etc/hadoop/conf.cloudera.yarn4:/run/cloudera-scm-agent/process/47188-yarn-NODEMANAGER:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-annotations.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-auth.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-aws.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-common-tests.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-common.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-nfs.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-nfs-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-common-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-common-2.6.0-cdh5.5.0-tests.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-aws-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-auth-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/hadoop-annotations-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-format.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-format-sources.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-format-javadoc.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-tools.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-thrift.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-test-hadoop2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-scrooge_2.10.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-scala_2.10.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-protobuf.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-pig.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-pig-bundle.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-jackson.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-hadoop.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-hadoop-bundle.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-generator.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-encoding.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-common.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-column.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-cascading.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/parquet-avro.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/hue-plugins-3.9.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-httpclient-3.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-math3-3.1.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-digester-1.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/curator-recipes-2.7.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-net-3.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-configuration-1.6.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/httpclient-4.2.5.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/gson-2.2.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-el-1.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jackson-xc-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/httpcore-4.2.5.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/curator-framework-2.7.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jersey-core-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jaxb-impl-2.2.3-1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jasper-compiler-5.5.23.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/htrace-core4-4.0.1-incubating.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-lang-2.6.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jsp-api-2.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jetty-util-6.1.26.cloudera.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jets3t-0.9.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jaxb-api-2.2.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jackson-mapper-asl-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/hamcrest-core-1.3.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-logging-1.1.3.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/apacheds-i18n-2.0.0-M15.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/zookeeper.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/avro.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/stax-api-1.0-2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/protobuf-java-2.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/mockito-all-1.8.5.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/log4j-1.2.17.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jsr305-3.0.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jetty-6.1.26.cloudera.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jersey-server-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/java-xmlbuilder-0.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jackson-jaxrs-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/guava-11.0.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-io-2.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/xmlenc-0.52.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/snappy-java-1.0.4.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/servlet-api-2.5.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/paranamer-2.3.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-compress-1.4.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-collections-3.2.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-codec-1.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-cli-1.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-beanutils-core-1.8.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/commons-beanutils-1.7.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/aws-java-sdk-1.7.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/asm-3.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/api-util-1.0.0-M20.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/api-asn1-api-1.0.0-M20.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/apacheds-kerberos-codec-2.0.0-M15.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/activation-1.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/slf4j-log4j12.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/xz-1.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/slf4j-api-1.7.5.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/netty-3.6.2.Final.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/logredactor-1.0.3.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/junit-4.11.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jsch-0.1.42.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jettison-1.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jersey-json-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jasper-runtime-5.5.23.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/jackson-core-asl-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop/lib/curator-client-2.7.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/hadoop-hdfs-nfs.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/hadoop-hdfs-tests.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/hadoop-hdfs.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/hadoop-hdfs-nfs-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/hadoop-hdfs-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/hadoop-hdfs-2.6.0-cdh5.5.0-tests.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/xmlenc-0.52.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/xml-apis-1.3.04.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/xercesImpl-2.9.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/servlet-api-2.5.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/protobuf-java-2.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/netty-3.6.2.Final.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/log4j-1.2.17.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/leveldbjni-all-1.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/jsr305-3.0.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/jsp-api-2.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/jetty-util-6.1.26.cloudera.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/jetty-6.1.26.cloudera.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/jersey-server-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/jersey-core-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/jasper-runtime-5.5.23.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/jackson-mapper-asl-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/jackson-core-asl-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/htrace-core4-4.0.1-incubating.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/guava-11.0.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/commons-logging-1.1.3.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/commons-lang-2.6.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/commons-io-2.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/commons-el-1.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/commons-daemon-1.0.13.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/commons-codec-1.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/commons-cli-1.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-hdfs/lib/asm-3.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-api.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-applications-distributedshell.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-applications-unmanaged-am-launcher.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-client.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-common.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-registry.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-applicationhistoryservice.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-common.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-nodemanager.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-resourcemanager.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-tests.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-web-proxy.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-web-proxy-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-tests-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-resourcemanager-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-nodemanager-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-common-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-server-applicationhistoryservice-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-registry-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-common-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-client-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-applications-unmanaged-am-launcher-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-applications-distributedshell-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/hadoop-yarn-api-2.6.0-cdh5.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/spark-yarn-shuffle.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/xz-1.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/servlet-api-2.5.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/protobuf-java-2.5.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/log4j-1.2.17.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/leveldbjni-all-1.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jsr305-3.0.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jline-2.11.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jetty-util-6.1.26.cloudera.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jetty-6.1.26.cloudera.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jettison-1.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jersey-server-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jersey-json-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jersey-guice-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jersey-core-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jersey-client-1.9.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jaxb-impl-2.2.3-1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jaxb-api-2.2.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/javax.inject-1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jackson-xc-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jackson-mapper-asl-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jackson-jaxrs-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/jackson-core-asl-1.8.8.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/guice-servlet-3.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/guice-3.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/guava-11.0.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/commons-logging-1.1.3.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/commons-lang-2.6.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/commons-io-2.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/commons-httpclient-3.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/commons-compress-1.4.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/commons-collections-3.2.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/commons-codec-1.4.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/commons-cli-1.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/asm-3.2.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/aopalliance-1.0.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/activation-1.1.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/zookeeper.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/spark-1.5.0-cdh5.5.0-yarn-shuffle.jar:/opt/cloudera/parcels/CDH-5.5.0-1.cdh5.5.0.p0.8/lib/hadoop-yarn/lib/stax-api-1.0-2.jar 16 2019-08-05 09:51:56,260 INFO org.apache.flink.runtime.entrypoint.ClusterEntrypoint - --------------------------------------------------------------------------------
看见了吧，去JobManager那台机器上对应目录下去找，可以看到日志所在文件夹
1 总用量 16K 2 drwx--x--- 3 yarn yarn 63 7月 25 17:58 application_1564048714696_0300 3 drwx--x--- 3 yarn yarn 63 7月 28 13:39 application_1564110901389_0235 4 drwx--x--- 4 yarn yarn 116 8月 5 09:52 application_1564969910131_0252 5 drwx--x--- 3 yarn yarn 63 8月 5 20:35 application_1564998210570_0394
这个是运行时日志，如果任务停止了呢，Yarn一般会有备份的，比如我这边用的Cloudera，有个配置
然后你用
1 hadoop fs -ls /tmp/logs/用户名/logs
发现日志都在。
4. Hadoop中的主要配置文件
core-site.xml：hadoop全局配置：HDFS路径 ，临时数据的公共目录，ZooKeeper集群的地址和端口。
<configuration>
<property>
<name>hadoop.tmp.dir</name>
<value>/usr/local/data/hadoop/tmp</value>
<!-- 其他临时目录的父目录 -->
</property>
<property>
<name>fs.defaultFS</name>
<value>hdfs://hadoop-alone:9000</value>
<!--
hdfs://host:port/
默认的文件系统的名称。通常指定namenode的URI地址，包括主机和端口
-->
</property>
<property>
<name>io.file.buffer.size</name>
<value>4096</value>
<!--
在序列文件中使用的缓冲区大小，这个缓冲区的大小应该是页大小（英特尔x86上为4096）的倍数
他决定读写操作中缓冲了多少数据（单位kb）
-->
</property>
<!--ZooKeeper集群的地址和端口。注意，数量一定是奇数，且不少于三个节点-->
<property>
<name>ha.zookeeper.quorum</name>
<value>hadoop1:2181,hadoop2:2181,hadoop3:2181,hadoop4:2181,hadoop5:2181</value>
</property>
</configuration>
hdfs-site.xml：HDFS文件系统属性：dfs.replication（文件块的数据备份数）， dfs.data.dir（datanode节点存储在文件系统的目录） ， dfs.name.dir（namenode节点存储在文件系统的目录） 。
<configuration>
<property>
<name>dfs.replication</name>
<value>3</value>
<!--指定dataNode存储block的副本数量，默认值是3个，该值应该不大于4-->
</property>
<property>
<name>dfs.blocksize</name>
<value>268435456</value>
<!--大型的文件系统HDFS块大小为256MB，先默认是128MB-->
</property>
<property>
<name>dfs.namenode.name.dir</name>
<value>file://${hadoop.tmp.dir}/dfs/name</value>
<!--
存放namenode的名称表（fsimage）的目录，如果这是一个逗号分隔的目录列表，
那么在所有目录中复制名称表，用于冗余。
-->
</property>
<property>
<name>dfs.datanode.data.dir</name>
<value>file://${hadoop.tmp.dir}/dfs/data</value>
<!--
存放datanode块的目录。如果这是一个逗号分隔的目录列表，
那么数据将存储在所有命名的目录中，通常存储在不同的设备上。
-->
</property>
<property>
<name>dfs.namenode.http-address</name>
<value>0.0.0.0:50070</value>
<!---->
</property>
<property>
<name>dfs.namenode.secondary.http-address</name>
<value>0.0.0.0:50090</value>
<!--secondary namenode HTTP服务器地址和端口。-->
</property>
<property>
<name>dfs.permissions</name>
<value>false</value>
</property>
<property>
<name>dfs.permissions.enabled</name>
<value>false</value>
<!-- 当为true时，则允许HDFS的检测，当为false时，则关闭HDFS的检测，但不影响其它HDFS的其它功能。-->
</property>
<property>
<name>dfs.nameservices</name>
<value>hadoop-cluster1</value>
<!--给hdfs集群起名字 -->
</property>
<property>
<name>dfs.namenode.handler.count</name>
<value>100</value>
<!-- RPC服务器的监听client线程数，如果dfs.namenode.servicerpc-address属性没有配置，则线程会监听所有节点的请求。-->
</property>
</configuration>
yarn-site.xml：设置Yarn的参数，NodeManager、ResourceManager等
<configuration>
<property>
<name>yarn.nodemanager.aux-services</name>
<value>mapreduce_shuffle</value>
</property>
<property>
<name>yarn.nodemanager.aux-services.mapreduce.shuffle.class</name>
<value>org.apache.hadoop.mapred.ShuffleHandler</value>
</property>
<property>
<name>yarn.resourcemanager.admin.address</name>
<value>hadoop-alone:8033</value>
</property>
<property>
<name>yarn.resourcemanager.resource-tracker.address</name>
<value>hadoop-alone:8025</value>
</property>
<property>
<name>yarn.resourcemanager.scheduler.address</name>
<value>hadoop-alone:8030</value>
</property>
<property>
<name>yarn.resourcemanager.address</name>
<value>hadoop-alone:8050</value>
</property>
<property>
<name>yarn.resourcemanager.scheduler.address</name>
<value>hadoop-alone:8030</value>
</property>
</configuration>
mapred-site.xml：指明MapReduce的运行框架为YARN；
<configuration>
<property>
<name>mapreduce.framework.name</name>
<value>yarn</value>
<!--执行框架设置为 Hadoop YARN.-->
</property>
</configuration>
hadoop-env.sh：设置jdk的安装路径
5. 使用distcp并行拷贝hdfs文件
hadoop distcp -bandwidth 50 hdfs://namenode:xxxx/源地址 hdfs://namenode:xxxx/目标地址
以上是关于Hadoop的NullWritable的主要内容，如果未能解决你的问题，请参考以下文章
Hadoop Serialization -- hadoop序列化具体解释 Text,BytesWritable,NullWritable