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batchmode_vb.vb
' 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. */ Imports System Imports Gurobi Class batchmode_vb ' Set-up the environment for batch mode optimization. ' ' The function creates an empty environment, sets all neccessary ' 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. Private Shared Function setupbatchenv() As GRBEnv Dim env As GRBEnv = New GRBEnv(True) env.CSBatchMode = 1 env.CSManager = "http://localhost:61080" env.LogFile = "batchmode.log" env.ServerPassword = "pass" env.UserName = "gurobi" ' 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 End Function ' Print batch job error information, if any Private Shared Sub printbatcherrorinfo(ByRef batch As GRBBatch) If batch.BatchErrorCode = 0 Then Return Console.WriteLine("Batch ID: " & batch.BatchID & ", Error code: " + batch.BatchErrorCode & "(" + batch.BatchErrorMessage & ")") End Sub ' Create a batch request for given problem file Private Shared Function newbatchrequest(ByVal filename As String) As String Dim batchID As String = "" ' Start environment, create Model object from file Dim env As GRBEnv = setupbatchenv() env.Start() Dim model As GRBModel = New GRBModel(env, filename) Try ' Set some parameters 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 Dim count As Integer = 0 For Each v As GRBVar In model.GetVars() v.VTag = "Variable" & count count += 1 If count >= 10 Then Exit For Next ' submit batch request batchID = model.OptimizeBatch() Finally model.Dispose() env.Dispose() End Try Return batchID End Function ' 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). Private Shared Sub waitforfinalstatus(ByVal batchID As String) ' Wait no longer than one hour Dim maxwaittime As Double = 3600 Dim start As DateTime = DateTime.Now ' Setup and start environment, create local Batch handle object Dim env As GRBEnv = setupbatchenv() env.Start() Dim batch As GRBBatch = New GRBBatch(env, batchID) Try While batch.BatchStatus = GRB.BatchStatus.SUBMITTED ' Abort this batch if it is taking too long Dim interval As TimeSpan = DateTime.Now - start If interval.TotalSeconds > maxwaittime Then batch.Abort() Exit While End If ' Wait for two seconds System.Threading.Thread.Sleep(2000) ' 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.BatchStatus.FAILED Then batch.Retry() System.Threading.Thread.Sleep(2000) batch.Update() End If End While Finally ' Print information about error status of the job that ' processed the batch printbatcherrorinfo(batch) batch.Dispose() env.Dispose() End Try End Sub Private Shared Sub printfinalreport(ByVal batchID As String) ' Setup and start environment, create local Batch handle object Dim env As GRBEnv = setupbatchenv() env.Start() Dim batch As GRBBatch = New GRBBatch(env, batchID) Select Case batch.BatchStatus Case GRB.BatchStatus.CREATED Console.WriteLine("Batch status is 'CREATED'" & vbLf) Case GRB.BatchStatus.SUBMITTED Console.WriteLine("Batch is 'SUBMITTED" & vbLf) Case GRB.BatchStatus.ABORTED Console.WriteLine("Batch is 'ABORTED'" & vbLf) Case GRB.BatchStatus.FAILED Console.WriteLine("Batch is 'FAILED'" & vbLf) Case GRB.BatchStatus.COMPLETED Console.WriteLine("Batch is 'COMPLETED'" & vbLf) ' Pretty printing the general solution information Console.WriteLine("JSON solution:" & batch.GetJSONSolution()) ' Write the full JSON solution string to a file batch.WriteJSONSolution("batch-sol.json.gz") Case Else ' Should not happen Console.WriteLine("Unknown BatchStatus" & batch.BatchStatus) Environment.[Exit](1) End Select batch.Dispose() env.Dispose() End Sub ' Instruct cluster manager to discard all data relating to this BatchID Private Shared Sub batchdiscard(ByVal batchID As String) ' Setup and start environment, create local Batch handle object Dim env As GRBEnv = setupbatchenv() env.Start() Dim batch As GRBBatch = New GRBBatch(env, batchID) ' Remove batch request from manager batch.Discard() batch.Dispose() env.Dispose() End Sub ' Solve a given model using batch optimization Shared Sub Main(ByVal args As String()) ' Ensure we have an input file If args.Length < 1 Then Console.Out.WriteLine("Usage: batchmode_vb filename") Return End If Try ' Submit new batch request Dim batchID As String = newbatchrequest(args(0)) ' Wait for final status waitforfinalstatus(batchID) ' Report final status info printfinalreport(batchID) ' Remove batch request from manager batchdiscard(batchID) Console.WriteLine("Batch optimization OK") Catch e As GRBException Console.WriteLine("Error code: " & e.ErrorCode & ". " + e.Message) End Try End Sub End Class