Visualizing DAGs

It can be helpful to see a picture of a DAG. DAGMan can assist you in visualizing a DAG by creating the input files used by the AT&T Research Labs graphviz package. dot is a program within this package, available from http://www.graphviz.org/, and it is used to draw pictures of DAGs.

DAGMan produces one or more dot files as the result of an extra line in a DAG input file. The line appears as

DOT dag.dot

This creates a file called dag.dot which contains a specification of the DAG before any jobs within the DAG are submitted to HTCondor. The dag.dot file is used to create a visualization of the DAG by using this file as input to dot. This example creates a Postscript file, with a visualization of the DAG:

$ dot -Tps dag.dot -o dag.ps

Within the DAG input file, the DOT command can take several optional parameters:

  • UPDATE This will update the dot file every time a significant update happens.

  • DONT-UPDATE Creates a single dot file, when the DAGMan begins executing. This is the default if the parameter UPDATE is not used.

  • OVERWRITE Overwrites the dot file each time it is created. This is the default, unless DONT-OVERWRITE is specified.

  • DONT-OVERWRITE Used to create multiple dot files, instead of overwriting the single one specified. To create file names, DAGMan uses the name of the file concatenated with a period and an integer. For example, the DAG input file line

    DOT dag.dot DONT-OVERWRITE

    causes files dag.dot.0, dag.dot.1, dag.dot.2, etc. to be created. This option is most useful when combined with the UPDATE option to visualize the history of the DAG after it has finished executing.

  • INCLUDE path-to-filename Includes the contents of a file given by path-to-filename in the file produced by the DOT command. The include file contents are always placed after the line of the form label=. This may be useful if further editing of the created files would be necessary, perhaps because you are automatically visualizing the DAG as it progresses.

If conflicting parameters are used in a DOT command, the last one listed is used.