DAGMan Completion
=================

.. sidebar:: Node Success/Failure

    **Table 2.1** Node **S**\ uccess or **F**\ ailure definition
    with :macro:`DAGMAN_ALWAYS_RUN_POST` = False (the default).

    +-----+-----------+-----------+-------+
    | PRE | Job(s)    | POST      | Node  |
    +=====+===========+===========+=======+
    | \-  | S         | \-        | **S** |
    +-----+-----------+-----------+-------+
    | \-  | F         | \-        | **F** |
    +-----+-----------+-----------+-------+
    | \-  | S         | S         | **S** |
    +-----+-----------+-----------+-------+
    | \-  | S         | F         | **F** |
    +-----+-----------+-----------+-------+
    | \-  | F         | S         | **S** |
    +-----+-----------+-----------+-------+
    | \-  | F         | F         | **F** |
    +-----+-----------+-----------+-------+
    | S   | S         | \-        | **S** |
    +-----+-----------+-----------+-------+
    | S   | F         | \-        | **F** |
    +-----+-----------+-----------+-------+
    | S   | S         | S         | **S** |
    +-----+-----------+-----------+-------+
    | S   | S         | F         | **F** |
    +-----+-----------+-----------+-------+
    | S   | F         | S         | **S** |
    +-----+-----------+-----------+-------+
    | S   | F         | F         | **F** |
    +-----+-----------+-----------+-------+
    | F   | not run   | \-        | **F** |
    +-----+-----------+-----------+-------+
    | F   | not run   | not run   | **F** |
    +-----+-----------+-----------+-------+

    **Table 2.2** Node **S**\ uccess or **F**\ ailure definition
    with :macro:`DAGMAN_ALWAYS_RUN_POST` = True

    +-----+-----------+--------+-------+
    | PRE | Job(s)    | POST   | Node  |
    +=====+===========+========+=======+
    | F   | not run   | \-     | **F** |
    +-----+-----------+--------+-------+
    | F   | not run   | S      | **S** |
    +-----+-----------+--------+-------+
    | F   | not run   | F      | **F** |
    +-----+-----------+--------+-------+

DAGMan exits the *condor_schedd* queue when it has successfully completed, or when
it can no longer make forward progress. The latter case is considered
failure. Successful completion happens when every node in the DAG has
successfully completed. In the case of a DAGMan failure, you can resubmit
the DAG so that only the incomplete work is run. Alternatively, you can
re-run a DAG from pre-specified save points, and re-run previously completed nodes.

.. _DAG node success:

Node Success/Failure
--------------------

Progress towards completion of the DAG is based upon the success of the
nodes within the DAG. The success of a node is based upon the success of
the associated job(s), PRE script, and POST script, where an exit value
not equal to 0 is considered failed. **The exit value of whatever component
of the node was run last determines the success or failure of the node.**

Table 2.1 lists the definition of node success and failure for all variations
of script and list of jobs success and failure, when :macro:`DAGMAN_ALWAYS_RUN_POST`
is set to ``False``. In this table, a dash (``-``) represents the case where a script
does not exist for the DAG, **S** represents success, and **F** represents
failure.

Table 2.2 lists the definition of node success and failure only for the cases
where the PRE script fails, when DAGMan is configured to always run POST scripts.

If a node contains more than one job, then the entire list of jobs is considered
a failure when any job in the list fails. Once declared as failed, the remaining
jobs associated with the node will be removed from the queue.

:index:`skipping node execution<single: DAGMan; Skipping node execution>`

.. _Node pre skip cmd:

PRE_SKIP
^^^^^^^^

The behavior of DAGMan with respect to node success or failure can be
changed with the addition of a :dag-cmd:`PRE_SKIP[Usage]` command. A *PRE_SKIP* line
within the DAG description file uses the syntax:

.. code-block:: condor-dagman

    PRE_SKIP <NodeName | ALL_NODES> non-zero-exit-code

The PRE script of a node identified by *NodeName* that exits with the
value given by *non-zero-exit-code* skips the remainder of the node
entirely. Neither the job(s) associated with the node nor the POST script
will be executed, and the node will be marked as successful.

:index:`retrying failed nodes<single: DAGMan; Retrying failed nodes>`

.. _Retry DAG Nodes:

Retrying Failed Nodes
^^^^^^^^^^^^^^^^^^^^^

DAGMan can retry any failed node in a DAG by specifying the node in the
DAG description file with the :dag-cmd:`RETRY[Usage]` command. The syntax for retry is

.. sidebar:: Example Diamond DAG Using RETRY

    .. code-block:: condor-dagman
        :caption: Example Diamond DAG description using node retries

        # File name: diamond.dag

        JOB  A  A.sub
        JOB  B  B.sub
        JOB  C  C.sub
        JOB  D  D.sub
        PARENT A CHILD B C
        PARENT B C CHILD D
        RETRY  C 3

    If marked as failed, node C will retry execution until either
    success or the maximum number of retries (3) are attempted.

.. code-block:: condor-dagman

    RETRY <NodeName | ALL_NODES> NumberOfRetries [UNLESS-EXIT value]

where *NodeName* identifies the node. *NumberOfRetries* is an integer
number of times to retry the node after failure.

The implied number of retries for any node is 0, the same as not having a
retry line in the file. Retry causes the whole node to be rerun (i.e. PRE
Script, entire list of jobs, and POST Script).

Retry of a node may be short-circuited using the optional keyword
*UNLESS-EXIT*, followed by an integer exit value. If the node exits with
the specified integer exit value, then no further processing will be
done on the node.

:index:`aborting a DAG<single: DAGMan; Aborting a DAG>`

.. _abort-dag-on:

Stopping the DAG on Node Failure
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The :dag-cmd:`ABORT-DAG-ON[Usage]` command provides a way to abort the entire DAG if a
given node returns a specific exit code. The syntax for :dag-cmd:`ABORT-DAG-ON`
is

.. sidebar:: Example Diamond DAG Using ABORT-DAG-ON

    .. code-block:: condor-dagman
        :caption: Example Diamond DAG description utilizing ABORT-DAG-ON command

        # File name: diamond.dag

        JOB  A  A.sub
        JOB  B  B.sub
        JOB  C  C.sub
        JOB  D  D.sub
        PARENT A CHILD B C
        PARENT B C CHILD D
        RETRY  C 3
        ABORT-DAG-ON C 10 RETURN 1

    If node C exits with return value 10 then the DAG is aborted with
    an exit value of 1.

.. code-block:: condor-dagman

    ABORT-DAG-ON <NodeName | ALL_NODES> AbortExitValue [RETURN DAGReturnValue]

If the return value for the specified node matches *AbortExitValue*, the DAG
is immediately aborted, meaning that the DAG stops all currently running nodes,
cleans up, writes a Rescue DAG, and exits with the optional specified return value.
If no DAG return value is specified, then DAGMan exits with the node return
value that caused the abort.

A DAG return value other than 0, 1, or 2 will cause the :tool:`condor_dagman`
job to stay in the queue after it exits and get retried, unless the
:subcom:`on_exit_remove` expression in the ``*.condor.sub`` file is manually
modified.

The behavior differs based on the existence of PRE and/or POST scripts:

- If a PRE script returns the *AbortExitValue* value, the DAG is immediately aborted.
- If any of the HTCondor jobs within a node returns the *AbortExitValue* value, the DAG is
  aborted if the node has no POST script.
- If the POST script returns the *AbortExitValue* value, the DAG is aborted.

.. note::

    An abort overrides node retries. If a node returns the abort exit value,
    the DAG is aborted, even if the node has retry specified.

Resubmitting a Failed DAG
-------------------------

.. sidebar:: Check DAG Successful Exit

    To determine successful completion of a DAG that has left the
    queue, the final line in the ``*.dagman.out`` file should appear
    similar to:

    .. code-block:: text

        (condor_DAGMAN) pid 445 EXITING WITH STATUS 0

DAGMan has two ways of restarting a failed DAG: Rescue and Recovery.
Rescue mode is most common for resubmitting a DAG manually, while recovery
mode is most likely to occur automatically if a crash or something similar occurs.

If the DAG has failed, it can be restarted such that work that needs
to be executed (including any previously failed part) is run. Resubmission should
be done via a Rescue DAG if the file exists; otherwise DAGMan will use
Recovery mode. To determine if Rescue mode is possible, check the DAG
working directory for a Rescue DAG. A Rescue DAG has a file name ending in
``.rescue<XXX>``, where ``<XXX>`` is replaced by a 3-digit number.

:index:`Rescue DAG<single: DAGMan; Rescue DAG>`

.. _Rescue DAG:

The Rescue DAG
^^^^^^^^^^^^^^

Any time a DAG exits unsuccessfully, DAGMan generates a Rescue DAG. The
Rescue DAG records the state of the DAG, with information such as which
nodes completed successfully, that will be used when the
DAG is again submitted. With the Rescue DAG, nodes that have already
successfully completed are not re-run. Nodes that are re-run will execute
every part of the node (PRE Script, job(s), and POST Script) even if
one part had previously completed successfully. There are a variety of
circumstances under which a Rescue DAG is generated:

.. sidebar:: Rescue DAG On Removal

    .. warning::

        On Windows no Rescue DAG is produced upon the removal of the DAGMan
        proper job, but re-submitting the original DAG will invoke recovery mode.

#. If a node in the DAG fails then DAGMan will continue executing until no more forward
   progress can be made. At this point, DAGMan produces the Rescue DAG and exits.
#. A Rescue DAG is produced when the :tool:`condor_dagman` job itself is removed via
   :tool:`condor_rm`. This only occurs on Unix platforms.
#. A Rescue DAG is produced when a node triggers an :dag-cmd:`ABORT-DAG-ON` with a non-zero
   exit value.

If the Rescue DAG file is generated before all retries of a node are
completed, then the Rescue DAG file will also contain :dag-cmd:`RETRY` entries.
The number of retries will be set to the appropriate remaining number of
retries. The configuration variable :macro:`DAGMAN_RESET_RETRIES_UPON_RESCUE`
controls whether or not node retries are reset in a Rescue DAG.

Statistics about the failed DAG execution are presented as comments at
the beginning of the Rescue DAG description file.

By default, if a Rescue DAG exists, it will be used when the DAG is
submitted specifying the original DAG description file. If more than one
Rescue DAG exists, the newest one will be used. By using the Rescue DAG,
DAGMan will avoid re-running nodes that completed successfully in the
previous run.

.. note::

    Passing the **-force** option to :tool:`condor_submit_dag` or
    :tool:`condor_dagman` will cause DAGMan to not use any existing
    Rescue DAGs. This means that previously-completed nodes will be re-run.

Rescue DAG Naming
'''''''''''''''''

.. sidebar:: Example Rescue Diamond DAG

    If the ``diamond.dag`` was submitted and failed then the Rescue DAG
    ``diamond.dag.rescue001`` should be produced. Simply resubmit the
    DAG to re-run in rescue mode.

    .. code-block:: console
        :caption: Example re-running failed DAG

        $ condor_submit_dag diamond.dag
            //Failure occurs
        $ ls
            diamond.dag diamond.dag.rescue001 ...
        $ condor_submit_dag diamond.dag

    If the resubmitted DAG fails again then ``diamond.dag.rescue002``
    should be produced. This will then be used with the next resubmission.

The file name of the Rescue DAG is ``<DAG Description File>.rescue<XXX>``, where ``<XXX>``
starts at ``001`` and increments with each new failure until the maximum value is hit.
The maximum value is defined by the configuration option :macro:`DAGMAN_MAX_RESCUE_NUM` .
If this limit is reached, then the last Rescue DAG file is overwritten upon failure of
the DAG.

If multiple independent DAGs are submitted at one time via :tool:`condor_submit_dag`,
then the Rescue DAG file will be named ``<Primary DAG>_multi.rescue<XXX>``, where
the primary DAG is the first DAG description file specified on the command line. This
multi-DAG rescue file will encompass all the nodes provided by the multiple
independent DAG files.

If a Rescue DAG exists when the original DAG is re-submitted, the Rescue
DAG with the largest magnitude value for ``<XXX>`` will be used, and its
usage is implied.

Using an Older Rescue DAG
'''''''''''''''''''''''''

If a DAG has failed multiple times and produced many Rescue DAG files, specific
Rescue DAGs can be specified to re-run the DAG from rather than the rescue with
the highest magnitude. This is achieved by using the *-DoRescueFrom* option or
*-RescueFile* option for :tool:`condor_submit_dag`.

.. code-block:: console
    :caption: Example re-running failed DAG from specific rescue file

    $ condor_submit_dag -RescueFile diamond.dag.rescue002 diamond.dag

.. code-block:: console
    :caption: Example re-running failed DAG from specific rescue number

    $ condor_submit_dag -DoRescueFrom 2 diamond.dag

When an older rescue file is specified and the DAG fails, all existing rescue DAG
files of a higher magnitude will be renamed with the ``.old`` suffix. So,
``diamond.dag.rescue003`` will become ``diamond.dag.rescue003.old``.

Special Cases
'''''''''''''

#. If multiple DAG description files are provided on the :tool:`condor_submit_dag`
   command line, a single Rescue DAG encompassing all of the input DAGs is
   generated. The primary DAG (the first DAG specified on the command line) will
   be used as the base of the Rescue DAG name.
#. A DAG file that contains DAG splices also only produces a single Rescue DAG
   file, since the spliced DAG nodes are inherited by the top-level DAG.
#. A DAG that contains sub-DAGs will produce one Rescue DAG file per sub-DAG,
   since each sub-DAG is its own job running in the queue along with the
   top-level DAG. The Rescue DAG files will be created relative to the specified
   DAG description files.

:index:`DAG recovery<single: DAGMan; DAG recovery>`

DAG Recovery
^^^^^^^^^^^^

DAG recovery restores the state of a DAG upon resubmission by reading the
``*.nodes.log`` file that is used to enforce the dependencies of the DAG.
Once the state is restored, DAGMan will continue the execution of the DAG.

Recovery is appropriate when no Rescue DAG has been created. The Rescue
DAG will fail to write if a crash occurs (Host machine, *condor_schedd*,
or :tool:`condor_dagman` job) or if the :tool:`condor_dagman` job is put
on hold.

Most of the time, when a not-completed DAG is re-submitted, it will
automatically be placed into recovery mode due to the existence and
contents of a lock file created as the DAG is first run. In recovery
mode, the ``*.nodes.log`` is used to identify nodes that have completed
and should not be re-submitted.

DAGMan can be told to work in recovery mode by including the
**-DoRecovery** option on the command line.

.. code-block:: console
    :caption: Example manually re-running DAG in recovery mode

    $ condor_submit_dag diamond.dag -DoRecovery

.. sidebar:: Example DAG Save Point Files

    Given the following DAG file, if run from the ``my_work`` directory,
    then the following save files will be produced:

    .. code-block:: condor-dagman
        :caption: Example DAG description using node save point files

        # File: savepointEx.dag
        JOB A node.sub
        JOB B node.sub
        JOB C node.sub
        JOB D node.sub

        PARENT A B C CHILD D

        #SAVE_POINT_FILE NodeName [Filename]
        SAVE_POINT_FILE A
        SAVE_POINT_FILE B Node-B_custom.save
        SAVE_POINT_FILE C ../example/Node-C_custom.save
        SAVE_POINT_FILE D ./Node-D_custom.save

    .. code-block:: text
        :caption: Example DAGMan working directory with node save point files

        Directory Tree Visualized
        └─Home
            ├─example
            │   └─Node-C_custom.save
            └─my_work
                ├─savepointEx.dag
                ├─savepointEx.dag.condor.sub
                ├─savepointEx.dag.dagman.out
                ├─...
                ├─Node-D_custom.save
                └─save_files
                      ├─ A-savepointEx.dag.save
                      └─ Node-B_custom.save

:index:`DAG save point file<single: DAGMan; DAG save point file>`

.. _DAG Save Files:

DAG Save Point Files
--------------------

A successfully completed DAG can be re-run from a specific saved state if
the DAG originally run contained save point nodes. Save point nodes are
DAG nodes that have an associated :dag-cmd:`SAVE_POINT_FILE[Usage]` command. The
:dag-cmd:`SAVE_POINT_FILE` syntax is as follows:

.. code-block:: condor-dagman
    :caption: DAG description SAVE_POINT_FILE command syntax

    SAVE_POINT_FILE NodeName [filename]

This file is written in the exact same format as the partial Rescue DAG
except all retries are reset. The save file is written as follows:

#. **When:**
    The save point file is written the first time a DAG node starts, meaning
    that it will not be written during a retry.

#. **Named:**
    If provided a filename, then DAGMan will write the status to that provided
    file name; otherwise the save file will be named ``[Node Name]-[DAG Description File].save``,
    where the DAG description file is the DAG file in which the save point was declared.

#. **Where:**
    If a path is provided in the save point filename, then DAGMan will attempt to
    write to that location. If the path is relative, then the file is written
    relative to the DAG's working directory. Otherwise, DAGMan will write
    the save file to a new directory called ``save_files`` which is created in
    the DAG's working directory.

.. note::

    The use of :tool:`condor_submit_dag`\s *-UseDagDir* option will affect
    where the ``save_files`` directory is created and where save files with
    relative paths are written, since *-UseDagDir* alters the DAG
    working directory.

Once a DAG has run and produced save point files, the DAG can be re-run from a
specific save point via the *-load_save* option for :tool:`condor_submit_dag`.
DAGMan will attempt to read the save file from any path that is provided;
otherwise DAGMan will assume the specified save file is located in the ``save_files``
directory. The path for the specified save file is checked relative to the
DAG's working directory.

If a save file already exists at the time DAGMan goes to write it, then DAGMan will
first rename the current file of the same name with the suffix ``.old``. This happens
whether the DAG is being re-run or the same save filename is used with multiple nodes,
allowing for a progressing save file. For example, a progressing save point file can
be set up as follows:

.. code-block:: condor-dagman
    :caption: Example DAG description with rolling save point file

    # File: progressSavefile.dag
    JOB A node.sub
    JOB B node.sub
    JOB C node.sub
    ...
    SAVE_POINT_FILE A dag-progress.save
    SAVE_POINT_FILE B dag-progress.save
    SAVE_POINT_FILE C dag-progress.save

.. mermaid::
    :align: center
    :caption: Progressing Save File DAG Actions

    flowchart LR
        subgraph A[Node A]
            w1[<font color="#08A04B">Write</font> dag-progress.save] --> r1((Run))
        end
        subgraph B[Node B]
            m1[<font color="blue">Rename</font> dag-progress.save<br>to dag-progress.save.old]
            w2[<font color="#08A04B">Write</font> dag-progress.save]
            m1 --> w2
            w2 --> r2((Run))
        end
        subgraph C[Node C]
            d[<font color="red">Remove</font> dag-progress.save.old]
            m2[<font color="blue">Rename</font> dag-progress.save<br>to dag-progress.save.old]
            w3[<font color="#08A04B">Write</font> dag-progress.save]
            d --> m2
            m2 --> w3
            w3 --> r3((Run))
        end
        A --> B
        B --> C
