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A Complete Example
#!/usr/bin/env python3.11 # Copyright 2024, 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 Compute Server license for this example to work. import sys import time import json import gurobipy as gp from gurobipy import GRB # Set up the environment for batch mode optimization. # # The function creates an empty environment, sets all necessary parameters, # and returns the ready-to-be-started Env object to caller. It is the # caller's responsibility to dispose of this environment when it's no # longer needed. def setupbatchenv(): env = gp.Env(empty=True) env.setParam("LogFile", "batchmode.log") env.setParam("CSManager", "http://localhost:61080") env.setParam("UserName", "gurobi") env.setParam("ServerPassword", "pass") env.setParam("CSBatchMode", 1) # No network communication happened up to this point. This will happen # once the caller invokes the start() method of the returned Env object. return env # Print batch job error information, if any def printbatcherrorinfo(batch): if batch is None or batch.BatchErrorCode == 0: return print( f"Batch ID {batch.BatchID}: Error code {batch.BatchErrorCode} ({batch.BatchErrorMessage})" ) # Create a batch request for given problem file def newbatchrequest(filename): # Start environment, create Model object from file # # By using the context handlers for env and model, it is ensured that # model.dispose() and env.dispose() are called automatically with setupbatchenv().start() as env, gp.read(filename, env=env) as model: # Set some parameters model.Params.MIPGap = 0.01 model.Params.JSONSolDetail = 1 # Define tags for some variables in order to access their values later for count, v in enumerate(model.getVars()): v.VTag = f"Variable{count}" if count >= 10: break # Submit batch request batchID = model.optimizeBatch() 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). def waitforfinalstatus(batchID): # Wait no longer than one hour maxwaittime = 3600 # Setup and start environment, create local Batch handle object with setupbatchenv().start() as env, gp.Batch(batchID, env) as batch: starttime = time.time() while batch.BatchStatus == GRB.BATCH_SUBMITTED: # Abort this batch if it is taking too long curtime = time.time() if curtime - starttime > maxwaittime: batch.abort() break # Wait for two seconds time.sleep(2) # Update the resident attribute cache of the Batch object with the # latest values from the cluster manager. batch.update() # If the batch failed, we retry it if batch.BatchStatus == GRB.BATCH_FAILED: batch.retry() # Print information about error status of the job that processed the batch printbatcherrorinfo(batch) def printfinalreport(batchID): # Setup and start environment, create local Batch handle object with setupbatchenv().start() as env, gp.Batch(batchID, env) as batch: if batch.BatchStatus == GRB.BATCH_CREATED: print("Batch status is 'CREATED'") elif batch.BatchStatus == GRB.BATCH_SUBMITTED: print("Batch is 'SUBMITTED") elif batch.BatchStatus == GRB.BATCH_ABORTED: print("Batch is 'ABORTED'") elif batch.BatchStatus == GRB.BATCH_FAILED: print("Batch is 'FAILED'") elif batch.BatchStatus == GRB.BATCH_COMPLETED: print("Batch is 'COMPLETED'") print("JSON solution:") # Get JSON solution as string, create dict from it sol = json.loads(batch.getJSONSolution()) # Pretty printing the general solution information print(json.dumps(sol["SolutionInfo"], indent=4)) # Write the full JSON solution string to a file batch.writeJSONSolution("batch-sol.json.gz") else: # Should not happen print("Batch has unknown BatchStatus") printbatcherrorinfo(batch) # Instruct the cluster manager to discard all data relating to this BatchID def batchdiscard(batchID): # Setup and start environment, create local Batch handle object with setupbatchenv().start() as env, gp.Batch(batchID, env) as batch: # Remove batch request from manager batch.discard() # Solve a given model using batch optimization if __name__ == "__main__": # Ensure we have an input file if len(sys.argv) < 2: print(f"Usage: {sys.argv[0]} filename") sys.exit(0) # Submit new batch request batchID = newbatchrequest(sys.argv[1]) # Wait for final status waitforfinalstatus(batchID) # Report final status info printfinalreport(batchID) # Remove batch request from manager batchdiscard(batchID) print("Batch optimization OK")