flink on yarn 踩過的坑

flink on yarn (不錯的blog):https://www.jianshu.com/p/1b05202c4fb6
啓動 ./yarn-session.sh
1.報錯：
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

解決方式：在 /etc/profile中添加

export HADOOP_CLASSPATH=`hadoop classpath`

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

執行wordcount上傳hdfs

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

2.報錯：**

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

**
出現這種原因有多種：
1.flink版本問題：https://stackoverflow.com/questions/48983319/failed-to-submit-jobgraph-apache-flink
2.hdfs 文件端口有問題：默認是9000

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