How to specify system property in hadoop except modify hadoop-env.sh?

Question

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

Advise

Can we see the command you are using to start your job? Are you using a ToolRunner or GenericOptionsParser at all? – Mauretania

Answer 1

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");

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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);

Mauretania

The reason is that I am using a library which need to get system property – Advise

I see, I've edited my answer to a potential solution for you. – Mauretania

Answer 2

The hadoop script invoke java class like this

exec "$JAVA" $JAVA_HEAP_MAX $HADOOP_OPTS $CLASS "$@"

so, we can pass system-wide property like this:

export HADOOP_OPTS="$HADOOP_OPTS -Dfoo=bar"

Hurtle