Pydoop applications are run via the pydoop submit command. To start, you will need a working Hadoop cluster. If you don’t have one available, you can bring up a single-node Hadoop cluster on your machine – see the Hadoop web site for instructions.
If your applications is contained in a single (local) file named wc.py, with an entry point called __main__ (see Writing Full-Featured Applications) you can run it as follows:
pydoop submit --upload-file-to-cache wc.py wc input output
where input (file or directory) and output (directory) are HDFS paths. Note that the output directory will not be overwritten: instead, an error will be generated if it already exists when you launch the program.
If your entry point has a different name, specify it via --entry-point.
The following table shows command line options for pydoop submit:
| Short | Long | Meaning |
|---|---|---|
| --num-reducers | Number of reduce tasks. Specify 0 to only perform map phase | |
| --no-override-home | Don’t set the script’s HOME directory to the $HOME in your environment. Hadoop will set it to the value of the ‘mapreduce.admin.user.home.dir’ property | |
| --no-override-env | Use the default python executable and environment instead of overriding HOME, PATH, LD_LIBRARY_PATH and PYTHONPATH | |
| --no-override-ld-path | Use the default LD_LIBRARY_PATH, instead of copying it from the client | |
| --no-override-pypath | Use the default PYTHONPATH, instead of copying it from the client | |
| --no-override-path | Use the default PATH, instead of copying it from the client | |
| --set-env | Set an environment variable for task. Specify it as VAR=value. | |
| -D | Set a Hadoop property, e.g., -D mapred.compress.map.output=true | |
| --python-zip | Additional python zip file | |
| --upload-file-to-cache | Upload and add this file to the distributed cache. | |
| --upload-archive-to-cache | Upload and add this archive file to the distributed cache. | |
| --log-level | Logging level | |
| --job-name | name of the job | |
| --python-program | python executable that should be used by the wrapper | |
| --pretend | Do not actually submit a job, print the generated config settings and the command line that would be invoked | |
| --hadoop-conf | Hadoop configuration file | |
| --disable-property-name-conversion | Do not adapt property names to the hadoop version used. | |
| --mrv2 | Use mapreduce v2 Hadoop Pipes framework. InputFormat and OutputFormat classes should be mrv2 compliant | |
| --local-fs | Use a patched pipes submitter to sidestep a Hadoop security bug triggered when using local file systems | |
| --do-not-use-java-record-reader | Disable java RecordReader | |
| --do-not-use-java-record-writer | Disable java RecordWriter | |
| --input-format | java classname of InputFormat. Default value depends on the mapreduce version used | |
| --output-format | java classname of OutputFormat. Default value depends on the mapreduce version used | |
| --job-conf | Set a Hadoop property, e.g., mapreduce.compress.map.output=true | |
| --libjars | Additional comma-separated list of jar files | |
| --cache-file | Add this HDFS file to the distributed cache as a file. | |
| --cache-archive | Add this HDFS archive file to the distributed cacheas an archive. | |
| --entry-point | Explicitly execute MODULE.ENTRY_POINT() in the launcher script. |
When working on a shared cluster where you don’t have root access, you might have a lot of software installed in non-standard locations, such as your home directory. Since non-interactive ssh connections do not usually preserve your environment, you might lose some essential setting like LD_LIBRARY_PATH.
For this reason, by default pydoop submit copies some environment variables to the driver script that launches the job on Hadoop. If this behavior is not desired, you can disable it via the --no-override-env command line option.