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Hadrian-Standalone is an application that wraps the Hadrian software library as a shell command. It reads data from Avro files, JSON files (each line of input is a complete JSON document), and CSV files (for PFA whose input schema is a record of primitives only).

It is good for simple shell-based workflows and testing.

It can also run Jython scripts with schemas in place of PFA files, as long as Antinous is included in the JAR (not the -exclude-antinous version). This is useful for testing Jython-based model producers before sending them to Hadrian-MR.

Before you begin…

Download the pre-built Hadrian-Standalone JAR with dependencies. This article was tested with Hadrian 0.8.3; newer versions should work with no modification.

Help document

A good place to start is Hadrian-Standalone’s own help text, which will always show the latest options.

% java -jar target/hadrian-standalone-0.8.3-jar-with-dependencies.jar --help
 
Usage: java -jar hadrian-standalone.jar [options] engineFileName.pfa|json|yaml|yml|py [inputFile.json|avro]

  -n <value> | --numberOfEngines <value>
        number of engines to run (default: 1)
  -i <value> | --inputFormat <value>
        input format: "avro" (default), "json", "json+schema", "csv", "csv+header"
  -o <value> | --outputFormat <value>
        output format: "avro" (default), "json", "json+schema", "csv", or "csv+header"
  -s baseNameOrPath | --saveState baseNameOrPath
        base file name for saving the scoring engine state (a directory, file name prefix, or both)
  --printTime
        print average time of action to standard error (approximately every 10 seconds, does not include data input/output)
  --debug
        print out auto-generated Java code for PFA engine
  engineFileName.pfa|json|yaml|yml|py
        scoring engine encoded in PFA (pfa|json|yaml|yml) or Python (py)
  inputFile.json|avro
        optional input files (if omitted, data are taken from standard input)
  --help
        print this help message

Hadrin standalone runs a PFA-encoded scoring engine as a standard
input to standard output process.  If multiple engines are specified,
these engines run in parallel and may share state.  If a --saveState
option is provided, the final state is written to a file at the end of
input.

Details

If --numberOfEngines is greater than 1, parallel threads are launched with one engine instance in each thread. Data from the inputFiles are processed sequentially, and the process ends when all input files have been processed. With parallel threads, the input data are given to the first non-busy scoring engine and the input stream waits if all engines are busy (scatter step). Output from the engines are collected on a single java.util.concurrent.ConcurrentLinkedQueue and are written to the output file in the order in which they are received. This is only equal to the input order if --numberOfEngines is 1.

The input and output files do not need to be files; they can be named pipes.