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batchmode_c++.cpp
/* Copyright 2023, Gurobi Optimization, LLC */
// This example reads a MIP model from a file, solves it in batch mode,
// and prints the JSON solution string.
//
// You will need a Cluster Manager license for this example to work.
#include <ctime>
#if defined (WIN32) || defined (WIN64) || defined(_WIN32) || defined (_WIN64)
#include <Windows.h>
#define sleep(n) Sleep(1000*n)
#else
#include <unistd.h>
#endif
#include "gurobi_c++.h"
using namespace std;
// Set-up the environment for batch mode optimization.
//
// The function configures and start an environment to be used for batch
// optimization.
void
setupbatchenv(GRBEnv* env)
{
env->set(GRB_StringParam_LogFile, "batchmode.log");
env->set(GRB_StringParam_CSManager, "http://localhost:61080");
env->set(GRB_StringParam_UserName, "gurobi");
env->set(GRB_StringParam_ServerPassword, "pass");
env->set(GRB_IntParam_CSBatchMode, 1);
// No network communication happened up to this point. This will happen
// now that we call the start() method.
env->start();
}
// Print batch job error information, if any
void
printbatcherrorinfo(GRBBatch &batch)
{
if (batch.get(GRB_IntAttr_BatchErrorCode) == 0)
return;
cerr << "Batch ID " << batch.get(GRB_StringAttr_BatchID)
<< ": Error code " << batch.get(GRB_IntAttr_BatchErrorCode)
<< " (" << batch.get(GRB_StringAttr_BatchErrorMessage)
<< ")" << endl;
}
// Create a batch request for given problem file
string
newbatchrequest(char* filename)
{
GRBEnv* env = NULL;
GRBModel* model = NULL;
GRBVar* v = NULL;
string batchID;
try {
// Start environment, create Model object from file
env = new GRBEnv(true);
setupbatchenv(env);
model = new GRBModel(*env, filename);
// Set some parameters; switch on detailed JSON information
model->set(GRB_DoubleParam_MIPGap, 0.01);
model->set(GRB_IntParam_JSONSolDetail, 1);
// Define tags for some variables in order to access their values later
int numvars = model->get(GRB_IntAttr_NumVars);
v = model->getVars();
if (numvars > 10) numvars = 10;
for (int j = 0; j < numvars; j++) {
char vtag[64];
sprintf(vtag, "Variable %d", j);
v[j].set(GRB_StringAttr_VTag, string(vtag));
}
// submit batch request
batchID = model->optimizeBatch();
} catch (...) {
// Free local resources
delete[] v;
delete model;
delete env;
// Let the exception propagate
throw;
}
// Free local resources
delete[] v;
delete model;
delete env;
return batchID;
}
// Wait for the final status of the batch.
// Initially the status of a batch is "submitted"; the status will change
// once the batch has been processed (by a compute server).
void
waitforfinalstatus(string batchID)
{
// Wait no longer than one hour
time_t maxwaittime = 3600;
GRBEnv* env = NULL;
GRBBatch* batch = NULL;
try {
// Setup and start environment, create local Batch handle object
env = new GRBEnv(true);
setupbatchenv(env);
batch = new GRBBatch(*env, batchID);
time_t starttime = time(NULL);
int BatchStatus = batch->get(GRB_IntAttr_BatchStatus);
while (BatchStatus == GRB_BATCH_SUBMITTED) {
// Abort this batch if it is taking too long
time_t curtime = time(NULL);
if (curtime - starttime > maxwaittime) {
batch->abort();
break;
}
// Wait for two seconds
sleep(2);
// Update the resident attribute cache of the Batch object with the
// latest values from the cluster manager.
batch->update();
BatchStatus = batch->get(GRB_IntAttr_BatchStatus);
// If the batch failed, we try again
if (BatchStatus == GRB_BATCH_FAILED)
batch->retry();
}
} catch (...) {
// Print information about error status of the job that
// processed the batch
printbatcherrorinfo(*batch);
// Free local resources
delete batch;
delete env;
// let the exception propagate
throw;
}
// Free local resources
delete batch;
delete env;
}
void
printfinalreport(string batchID)
{
GRBEnv* env = NULL;
GRBBatch* batch = NULL;
try {
// Setup and starts environment, create local Batch handle object
env = new GRBEnv(true);
setupbatchenv(env);
batch = new GRBBatch(*env, batchID);
int BatchStatus = batch->get(GRB_IntAttr_BatchStatus);
if (BatchStatus == GRB_BATCH_CREATED)
cout << "Batch status is 'CREATED'" << endl;
else if (BatchStatus == GRB_BATCH_SUBMITTED)
cout << "Batch is 'SUBMITTED" << endl;
else if (BatchStatus == GRB_BATCH_ABORTED)
cout << "Batch is 'ABORTED'" << endl;
else if (BatchStatus == GRB_BATCH_FAILED)
cout << "Batch is 'FAILED'" << endl;
else if (BatchStatus == GRB_BATCH_COMPLETED) {
cout << "Batch is 'COMPLETED'" << endl;
// Pretty printing the general solution information
cout << "JSON solution:" << batch->getJSONSolution() << endl;
// Write the full JSON solution string to a file
batch->writeJSONSolution("batch-sol.json.gz");
} else {
// Should not happen
cout << "Batch has unknown BatchStatus" << endl;
}
} catch (...) {
// Free local resources
delete batch;
delete env;
// let the exception propagate
throw;
}
// Free local resources
delete batch;
delete env;
}
// Instruct cluster manager to remove all data relating to this BatchID
void
batchdiscard(string batchID)
{
GRBEnv* env = NULL;
GRBBatch* batch = NULL;
try {
// Setup and start environment, create local Batch handle object
env = new GRBEnv(true);
setupbatchenv(env);
batch = new GRBBatch(*env, batchID);
// Remove batch request from manager
batch->discard();
} catch (...) {
// Free local resources even
delete batch;
delete env;
// let the exception propagate
throw;
}
// Free local resources
delete batch;
delete env;
}
// Solve a given model using batch optimization
int
main(int argc,
char** argv)
{
// Ensure we have an input file
if (argc != 2) {
cout << "Usage: " << argv[0] << " filename" << endl;
return 0;
}
try {
// Submit new batch request
string batchID = newbatchrequest(argv[1]);
// Wait for final status
waitforfinalstatus(batchID);
// Report final status info
printfinalreport(batchID);
// Remove batch request from manager
batchdiscard(batchID);
cout << "Batch optimization OK" << endl;
} catch (GRBException e) {
cout << "Error code = " << e.getErrorCode() << endl;
cout << e.getMessage() << endl;
} catch (...) {
cout << "Exception during optimization" << endl;
}
return 0;
}
