Try our new documentation site (beta).
batchmode_vb.vb
' 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. */
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
