Dumping and Restoring¶

This page gives an overview of dumping and restoring

During normal operation QHG only creates partial outputs of its state: files containing the environment or agent data for a particular time.

QHG also supports dumping (writing a snapshot of the complete internal state of the program to file) and restoring (reading a snapshot of the complete internal state of the program from file).

This lets you exactly reproduce a simualtion run, allowing to write more outputs or even to debug something happening very late in the simulation.

Every action can dump and restore its state:

template<typename T>
class Action {
public:
    // ...
    virtual int dumpStateQDF(hid_t hSpeciesGroup) {return 0; };
    virtual int restoreStateQDF(hid_t hSpeciesGroup) {return 0; };
    // ...
}

and every population can dump and restore the population data, the individual agents’ data, move statistics and additional data:

class PopBase {
public:
    // ...
    virtual int dumpSpeciesDataQDF(hid_t hSpeciesGroup, int iDumpMode)=0;
    virtual int restoreSpeciesDataQDF(hid_t hSpeciesGroup)=0;
    virtual int dumpAgentDataQDF(hid_t hDataSpace, hid_t hDataSet, hid_t hAgentType)=0;
    virtual int restoreAgentDataQDF(hid_t hDataSpace, hid_t hDataSet, hid_t hAgentType)=0;
    virtual int dumpStatArrsQDF(hid_t hSpeciesGroup)=0;
    virtual int restoreStatArrsQDF(hid_t hSpeciesGroup)=0;
    virtual int dumpAdditionalDataQDF(hid_t hSpeciesGroup)=0;
    virtual int restoreAdditionalDataQDF(hid_t hSpeciesGroup)=0;
    // ...
}

The easiest way to create a dump pass an event to start the simulation:

--events='dump|flat'

This will create a QDF file containning the environment dump, as well as a QDF dump file for every population in he simulation.

To restore a dumped simulation, you hav to start QHG with the dumped files and the “resume” option:

--grid=environment_dump.qdf
--pops=population1_dump.qdf,population2_dump.qdf
--resume

Keep in mind that the number of processors for the restoreed run must be the same as in the original run. Otherwise the random numbers quickly got out of synch.