如何在hadoop中指定系统属性，除了修改hadoop-env.sh？ [英] How to specify system property in hadoop except modify hadoop-env.sh?

问题描述

我想在运行hadoop作业时设置系统属性（不是hadoop属性）。我发现设置系统属性并不容易。即使我在shell中设置属性

  export HADOOP_OPTS =$ HADOOP_OPTS：-Dproperty = value
  

这仍然不起作用。 hadoop命令行的-D选项仅用于配置，而不是系统属性。所以-D选项也不起作用。

任何人有想法？谢谢

解决方案

为什么不简单地使用 -Dfoo.bar = example 当通过命令行启动作业时，如下所示：

hadoop jar example.jar com.example.ExampleTool -Dfoo.bar = example参数

为了获得代码中的属性，使用 conf.get（foo.bar） ;

---

现在，如果您真的需要将其设置为系统属性，

  String property = conf.get（ foo.bar）; 
 System.setProperty（foo.bar，property）; 
  

I'd like to set system property (not hadoop property) when running hadoop jobs. I found that it's not easy to setting system property. Even I set the property in shell

export HADOOP_OPTS="$HADOOP_OPTS:-Dproperty=value"

It's still not working. The "-D" option of hadoop command line is only for Configuration, not system property. So the "-D" option also not working

Anyone has ideas ? thanks

解决方案

Why not simply use -Dfoo.bar=example in-line when starting the job via command line, like so:

hadoop jar example.jar com.example.ExampleTool -Dfoo.bar=example argument

In order to get at the property in code, use conf.get("foo.bar");

---

Now if you genuinely need it to be set as a system property, you can set it at the start of your code using the value you got from Hadoop config like so:

String property = conf.get("foo.bar");
System.setProperty("foo.bar", property);

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