A training algorithm indicates whether it succeeded or failed using the exit code of its process.
A successful training execution should exit with an exit code of 0 and an unsuccessful
training execution should exit with a non-zero exit code. These will be converted to
Completed and Failed in the TrainingJobStatus
returned by DescribeTrainingJob. This exit code convention is standard and
is easily implemented in all languages. For example, in Python, you can use
sys.exit(1) to signal a failure exit, and simply running to the end of
the main routine will cause Python to exit with code 0.
In the case of failure, the algorithm can write a description of the failure to the failure file. See next section for details.
