flink on yarn 踩过的坑

flink on yarn (不错的blog):https://www.jianshu.com/p/1b05202c4fb6 启动 ./yarn-session.sh 1.报错： Error: A JNI error has occurred, please check your installation and try again

Error: A JNI error has occurred, please check your installation and try again Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/yarn/exceptions/YarnException at java.lang.Class.getDeclaredMethods0(Native Method) at java.lang.Class.privateGetDeclaredMethods(Class.java:2701) at java.lang.Class.privateGetMethodRecursive(Class.java:3048) at java.lang.Class.getMethod0(Class.java:3018) at java.lang.Class.getMethod(Class.java:1784) at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:544) at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:526) Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.yarn.exceptions.YarnException at java.net.URLClassLoader.findClass(URLClassLoader.java:382) 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) ... 7 more

解决方式：在 /etc/profile中添加

export HADOOP_CLASSPATH=`hadoop classpath`

记得source /etc/profile 参考地址：https://ci.apache.org/projects/flink/flink-docs-release-1.9/ops/deployment/hadoop.html#hadoop-integration

执行wordcount上传hdfs

`/bin/flink run ./examples/batch/WordCount.jar -input hdfs://centos-200:8020/LICENSE -output hdfs://centos-200:8020/wordcount-result_1.txt`

2.报错：**

Caused by: org.apache.flink.runtime.client.JobSubmissionException: Failed to submit JobGraph. Caused by: java.net.ConnectException: Connection refused

** 出现这种原因有多种： 1.flink版本问题：https://stackoverflow.com/questions/48983319/failed-to-submit-jobgraph-apache-flink 2.hdfs 文件端口有问题：默认是9000

<property> <name>fs.defaultFS</name> <value>hdfs://node01:9000</value> </property>