Batched Evaluations
Dakota provides for execution of evaluations in batches.
Batch mode is intended to allow a user to assume greater control over where
and when to run individual evaluations. It is activated using the batch
keyword.
In batch mode, Dakota writes the parameters for multiple (a batch of) evaluations to a single batch parameters file and then invokes the analysis driver once for the entire batch. The pathname of the combined parameters file (and of the results file) are communicated to the driver as command line arguments. After the driver exits, Dakota expects to find results for the entire batch in a single combined results file.
The analysis driver is responsible for parsing the parameters file and performing an evaluation for each set of parameters it contains, and for returning results for all the evaluations to Dakota. The user is free to set up the driver to perform the evaluations in the batch in a way that is convenient.
By default, all currently available evaluations are added to a single
batch. For example, in a sampling study that has a 1000 samples, by
default all 1000 evaluations would be added to a single batch. The batch
size may be limited using the size
subkeyword. Setting
size = 100
would result in 10 equal-size batches being run one after
another in a 1000-sample study.
File Formats
The combined parameters file for a batch is simply the concatenation of all the parameters files for the evaluations in the batch. The individual parameter sets may use the default Dakota format, or the user can select the aprepro format.
The following example parameters file contains parameter sets for two evaluations.
1 variables
-4.912558193411678e-01 x1
1 functions
1 ASV_1:response_fn_1
1 derivative_variables
1 DVV_1:x1
0 analysis_components
1:1 eval_id
1 variables
-2.400695372000337e-01 x1
1 functions
1 ASV_1:response_fn_1
1 derivative_variables
1 DVV_1:x1
0 analysis_components
1:2 eval_id interface,
Note that the eval_id
contains two pieces of information separated
by a colon. The second is the evaluation number, and the first is the
batch number. The batch number is an incrementing integer that uniquely
identifies the batch.
The combined results file format is likewise a concatenation of the results for all the evaluations in the batch. However, a line beginning with the “#” character must separate the results for each evaluation.
The order of the evaluations in the results file must match the order in the parameters file.
The following is an example batch results file corresponding to the batch parameters file above. The initial # on the first line is optional, and a final # (not shown here) is allowed.
#
4.945481774823024e+00 f
#
2.364744129789246e+00 f
Work Directories, Tagging, and Other Features
Each batch is executed in a work directory when this feature is enabled. The batch number is used to tag files and directories if tagging is requested (or Dakota automatically applies a tag to safely save a file or directory). As explained in the previous section, the batch number is an incrementing integer beginning with 1 that uniquely identifies a batch.
Batch mode restricts the use of several other Dakota features:
No
input_filter
oroutput_filter
is allowed.Only one
analysis_drivers
keyword is permitted.failure_capture
modes are limited to abort and recover.Asynchronous evaluation is disallowed (only one batch at a time may be executed).