pegasus-exitcode — Checks the stdout/stderr files of a workflow job for any indication that an error occurred in the job. This script is intended to be invoked automatically by DAGMan as the POST script of a job.
pegasus-exitcode is a utility that examines the STDOUT of a job to determine if the job failed, and renames the STDOUT and STDERR files of a job to preserve them in case the job is retried.
Pegasus uses pegasus-exitcode as the DAGMan postscript for all jobs submitted via Globus GRAM. This tool exists as a workaround to a known problem with Globus where the exitcodes of GRAM jobs are not returned. This is a problem because Pegasus uses the exitcode of a job to determine if the job failed or not.
In order to get around the exitcode problem, Pegasus wraps all GRAM jobs with Kickstart, which records the exitcode of the job in an XML invocation record, which it writes to the job’s STDOUT. The STDOUT is transferred from the execution host back to the submit host when the job terminates. After the job terminates, DAGMan runs the job’s postscript, which Pegasus sets to be pegasus-exitcode. pegasus-exitcode looks at the invocation record generated by kickstart to see if the job succeeded or failed. If the invocation record indicates a failure, then pegasus-exitcode returns a non-zero result, which indicates to DAGMan that the job has failed. If the invocation record indicates that the job succeeded, then pegasus-exitcode returns 0, which tells DAGMan that the job succeeded.
pegasus-exitcode performs several checks to determine whether a job failed or not. These checks include:
- Is STDOUT empty? If it is empty, then the job failed.
Are there any
<status>tags with a non-zero value? If there are, then the job failed. Note that, if this is a clustered job, there could be multiple
<status>tags, one for each task. If any of them are non-zero, then the job failed.
Is there at least one
<status>tag with a zero value? There must be at least one successful invocation or the job has failed.
In addition, pegasus-exitcode allows the caller to specify the exitcode
returned by Condor using the --return argument. This can be passed to
pegasus-exitcode in a DAGMan post script by using the
If this value is non-zero, then pegasus-exitcode returns a non-zero result
before performing any other checks. For GRAM jobs, the value of
always be 0 regardless of whether the job failed or not.
Also, pegasus-exitcode allows the caller to specify the number of successful tasks it should see using the --tasks argument. If pegasus-exitcode does not see N successful tasks, where N is set by --tasks, then it will return a non-zero result. The default value is 1. This can be used to detect failures in clustered jobs where, for any number of reasons, invocation records do not get generated for all the tasks in the clustered job.
In addition to checking the success/failure of a job, pegasus-exitcode also renames the STDOUT and STDERR files of the job so that if the job is retried, the STDOUT and STDERR of the previous run are not lost. It does this by appending a sequence number to the end of the files. For example, if the STDOUT file is called "job.out", then the first time the job is run pegasus-exitcode will rename the file "job.out.000". If the job is run again, then pegasus-exitcode sees that "job.out.000" already exists and renames the file "job.out.001". It will continue to rename the file by incrementing the sequence number every time the job is executed.
- -h , --help
- Prints a usage summary with all the available command-line options.
- -t n , --tasks n
- Number of tasks expected. If less than n tasks succeeded, then pegasus-exitcode will fail with a non-zero return value. This is used in cases where we may not get a Kickstart invocation record for some tasks. Normally Seqexec will detect failed Kickstart invocations and fail accordingly.
- -r rv , --return rv
- Return value reported by DAGMan. This can be specified in the DAG using the $RETURN variable. If this is non-zero, then pegasus-exitcode immediately fails with a non-zero return value itself.
- -n , --no-rename
- Don’t rename job.out and job.err to .out.XXX and .err.XXX. This option is used primarily for testing.
Pegasus Team http://pegasus.isi.edu