---
layout: default
navsection: api
navmenu: Schema
title: Job

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Applications submit compute jobs when:
* Provenance is important, i.e., it is worth recording how the output was produced; or
* Computation time is significant; or
* The job management features are convenient (failure detection/recovery, regression testing, etc).

h2. Methods

See "jobs":{{site.baseurl}}/api/methods/jobs.html

h2. Resource

Each job has, in addition to the usual "attributes of Arvados resources":{{site.baseurl}}/api/resources.html:

table(table table-bordered table-condensed).
|_. Attribute|_. Type|_. Description|_. Notes|
|script|string|The filename of the job script.|This program will be invoked by Crunch for each job task. It is given as a path to an executable file, relative to the @/crunch_scripts@ directory in the Git tree specified by the _repository_ and _script_version_ attributes.|
|script_parameters|hash|The input parameters for the job.|Conventionally, one of the parameters is called @"input"@. Typically, some parameter values are collection UUIDs. Ultimately, though, the significance of parameters is left entirely up to the script itself.|
|repository|string|Git repository|Given as the name of a locally hosted git repository.|
|script_version|string|Git commit|During a **create** transaction, this is the Git branch, tag, or hash supplied by the client. Before the job starts, Arvados updates it to the full 40-character SHA-1 hash of the commit used by the job.
See "Script versions":#script_version below for more detail about acceptable ways to specify a commit.|
|cancelled_by_client_uuid|string|API client ID|Is null if job has not been cancelled|
|cancelled_by_user_uuid|string|Authenticated user ID|Is null if job has not been cancelled|
|cancelled_at|datetime|When job was cancelled|Is null if job has not been cancelled|
|started_at|datetime|When job started running|Is null if job has not [yet] started|
|finished_at|datetime|When job finished running|Is null if job has not [yet] finished|
|running|boolean|Whether the job is running||
|success|boolean|Whether the job indicated successful completion|Is null if job has not finished|
|is_locked_by_uuid|string|UUID of the user who has locked this job|Is null if job is not locked. The system user locks the job when starting the job, in order to prevent job attributes from being altered.|
|log|string|Collection UUID|Is null if the job has not finished. After the job runs, the given collection contains a text file with log messages provided by the @arv-crunch-job@ task scheduler as well as the standard error streams provided by the task processes.|
|tasks_summary|hash|Summary of task completion states.|Example: @{"done":0,"running":4,"todo":2,"failed":0}@|
|output|string|Collection UUID|Is null if the job has not finished.|
|nondeterministic|boolean|The job is expected to produce different results if run more than once.|If true, this job will not be considered as a candidate for automatic re-use when submitting subsequent identical jobs.|
|submit_id|string|Unique ID provided by client when job was submitted|Optional. This can be used by a client to make the "jobs.create":{{site.baseurl}}/api/methods/jobs.html#create method idempotent.|
|priority|string|||
|runtime_constraints|hash|Constraints that must be satisfied by the job/task scheduler in order to run the job.|See below.|

h3(#script_version). Script versions

The @script_version@ attribute is typically given as a branch, tag, or commit hash, but there are many more ways to specify a Git commit. The "specifying revisions" section of the "gitrevisions manual page":http://git-scm.com/docs/gitrevisions.html has a definitive list. Arvados accepts @script_version@ in any format listed there that names a single commit (not a tree, a blob, or a range of commits). However, some kinds of names can be expected to resolve differently in Arvados than they do in your local repository. For example, <code>HEAD@{1}</code> refers to the local reflog, and @origin/master@ typically refers to a remote branch: neither is likely to work as desired if given as a @script_version@.

h3. Runtime constraints

table(table table-bordered table-condensed).
|_. Key|_. Type|_. Description|_. Implemented|
|min_nodes|integer||&#10003;|
|max_nodes|integer|||
|max_tasks_per_node|integer|Maximum simultaneous tasks on a single node|&#10003;|
|min_ram_per_task|integer|Minimum real memory (KiB) per task||
|min_ram_per_node|integer|Minimum real memory (KiB) per node||