Many of RoadRunner classes use a number of configuration parameters. Most of these can be set using the Config class. The values stored in the Config class only determine the default values of parameters. The Config class will look in the following locations for the config file, and will load the values from the first config file it finds. If it does not find a config file in one of the following locations, a default set of configuration parameters are used. The search locations of the config file are:

  1. The ROADRUNNER_CONFIG environment variable

  2. Try the user’s home directory for roadrunner.conf, i.e.:

  3. Try the user’s home directory for .roadrunner.conf, i.e.:


4. Try the same directory as the roadrunner shared library, this will be the same directory as the python _roadrunner.pyd python extension module, i.e.:

  1. try one directory up from the where the shared library or program is at, i.e.:


The conf file is just a plain text file of where each line may be key / value pair separated by a “:”, i.e.

KEY_NAME : Value

Any line that does not match this format is ignored, and keys that are not found are also ignored. Therefore, any line that does not start with a word character is considered a comment.

All of the configuration management functions are static method of the Config class, and all of the configuration keys are static attributes of the Config class, these are documented in the Configuration Functions section.

As all of the Config class methods are static, one never instantiates the Config class.

Configuration Functions

static Config.setValue(key, value)

Set the value of a configuration key. The value must be either a string, integer, double or boolean. If one wanted to turn off moiety conservation (this will not have an effect on already loaded models):

from roadrunner import Config

Or, other options may be set to Boolean or integer values. To enable an optimization features:

static Config.getConfigFilePath()

If roadrunner was able to find a configuration file on the file system, its full path is returned here. If no file was found, this returns a empty string.

static Config.readConfigFile(path)

Read all of the values from a configuration file at the given path. This overrides any previously stored configuration. This allows users to have any number of configuration files and load them at any time. Say someone had to use Windows, and they had a file in their C: drive, this would be loaded via:


Note, the forward slash works on both Unix and Windows, using the forward slash eliminates the need to use a double back slash, “\\”.

static Config.writeConfigFile(path)

Write all of the current configuration values to a file. This could be written to one of the default locations, or to any other location, and re-loaded at a later time.

Available Configuration Parameters

All of the configuration parameter keys are static attributes of the Config class and are listed here. The variable type of the parameter is listed after the key name.


Perform conservation analysis. By default, this attribute is set as False.

This causes a re-ordering of the species, so results generated with this flag enabled can not be compared index wise to results generated otherwise.

Moiety conservation is only compatible with simple models which do NOT have any events or rules which define or alter any floating species, and which have simple constant stoichiometries.

Moiety conservation may cause unexpected results, be aware of what it is before enabling.

Not recommended for time series simulations.

To enable, type:

>>> roadrunner.Config.setValue(roadrunner.Config.LOADSBMLOPTIONS_CONSERVED_MOIETIES, True)

Should the model be recompiled? The LLVM ModelGenerator maintains a hash table of currently running models. If this flag is NOT set, then the generator will look to see if there is already a running instance of the given model and use the generated code from that one.

If only a single instance of a model is run, there is no need to cache the models, and this can safely be enabled, realizing some performance gains.


If this is set, then a read-only model is generated. A read-only model can be simulated, but no code is generated to set model values, i.e. parameters, amounts, values, etc…

It takes a finite amount of time to generate the model value setting functions, and if they are not needed, one may see some performance gains, especially in very large models.


Generate accessors functions to allow changing of initial conditions.


GVN - This pass performs global value numbering and redundant load elimination contemporaneously.


CFGSimplification - Merge basic blocks, eliminate unreachable blocks, simplify terminator instructions, etc…


InstructionCombining - Combine instructions to form fewer, simple instructions. This pass does not modify the CFG, and has a tendency to make instructions dead, so a subsequent DCE pass is useful.


DeadInstElimination - This pass quickly removes trivially dead instructions without modifying the CFG of the function. It is a BasicBlockPass, so it runs efficiently when queued next to other BasicBlockPass’s.


DeadCodeElimination - This pass is more powerful than DeadInstElimination, because it is worklist driven that can potentially revisit instructions when their other instructions become dead, to eliminate chains of dead computations.


InstructionSimplifier - Remove redundant instructions.


Currently disabled.

Use the LLVM MCJIT JIT engine.

Defaults to false.

The MCJIT is the new LLVM JIT engine, it is not as well tested as the original JIT engine. Does NOT work on LLVM 3.1


RoadRunner by default dynamically generates accessors properties for all SBML symbol names on the model object when it is retrieved in Python. This feature is very nice for interactive use, but can slow things down. If this feature is not needed, it can be disabled here.


Disable SBML conserved moiety warnings.

Conserved Moiety Conversion may cause unexpected behavior, be aware of what it is before enabling.

RoadRunner will issue a warning in steadyState if conservedMoieties are NOT enabled because of a potential singular Jacobian. To disable this warning, set this value to 1

A notice will be issued whenever a document is loaded and conserved moieties are enabled. To disable this notice, set this value to 2.

To disable both the warning and notice, set this value to 3

Rationale for these numbers: This is actual a bit field, disabling the steady state warning value is actually 0b01 << 0 which is 1, and the loading warning is 0b01 << 1 which is 2 and 0b01 & 0b10 is 0b11 which is 3 in decimal.


Accept some non-valid SBML (such as Booleans in numberic expressions).

For legacy code only. Do not use.


Set the maximum number of rows in the output matrix.

For models with very fine time stepping, the output of simulate can use up all available memory and crash the system. This option provides an upper bound on the maximum number of rows the output can contain. The simulation will be aborted and the output truncated if this value is exceeded.


Enable or disable steady state calculations when a model contains events

If true, steady state calculations will be carried out irrespective of whether events are present or not. If false, steady state calculations will not be carried out in the presence of events.