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// Create a StartTask for the pool which we use for installing MS-MPI on // the nodes as they join the pool (or when they are restarted). StartTask startTask = new StartTask { CommandLine = "cmd /c MSMpiSetup.exe -unattend -force", ResourceFiles = new List<ResourceFile> { new ResourceFile("https://mystorageaccount.blob.core.windows.net/mycontainer/MSMpiSetup.exe", "MSMpiSetup.exe") }, UserIdentity = new UserIdentity(new AutoUserSpecification(elevationLevel: ElevationLevel.Admin)), WaitForSuccess = true }; myCloudPool.StartTask = startTask; // Commit the fully configured pool to the Batch service to actually create // the pool and its compute nodes. await myCloudPool.CommitAsync();

CloudPool myCloudPool = myBatchClient.PoolOperations.CreatePool( poolId: "MultiInstanceSamplePool", targetDedicatedComputeNodes: 3 virtualMachineSize: "standard_d1_v2", VirtualMachineConfiguration: new VirtualMachineConfiguration( imageReference: new ImageReference( publisher: "MicrosoftWindowsServer", offer: "WindowsServer", sku: "2019-datacenter-core", version: "latest"), nodeAgentSkuId: "batch.node.windows amd64"); // Multi-instance tasks require inter-node communication, and those nodes // must run only one task at a time. myCloudPool.InterComputeNodeCommunicationEnabled = true; myCloudPool.TaskSlotsPerNode = 1;

// Create the multi-instance task. Its command line is the "application command" // and will be executed *only* by the primary, and only after the primary and // subtasks execute the CoordinationCommandLine. CloudTask myMultiInstanceTask = new CloudTask(id: "mymultiinstancetask", commandline: "cmd /c mpiexec.exe -wdir %AZ_BATCH_TASK_SHARED_DIR% MyMPIApplication.exe"); // Configure the task's MultiInstanceSettings. The CoordinationCommandLine will be executed by // the primary and all subtasks. myMultiInstanceTask.MultiInstanceSettings = new MultiInstanceSettings(numberOfNodes) { CoordinationCommandLine = @"cmd /c start cmd /c ""%MSMPI_BIN%\smpd.exe"" -d", CommonResourceFiles = new List<ResourceFile> { new ResourceFile("https://mystorageaccount.blob.core.windows.net/mycontainer/MyMPIApplication.exe", "MyMPIApplication.exe") } }; // Submit the task to the job. Batch will take care of splitting it into subtasks and // scheduling them for execution on the nodes. await myBatchClient.JobOperations.AddTaskAsync("mybatchjob", myMultiInstanceTask);

// Obtain the job and the multi-instance task from the Batch service CloudJob boundJob = batchClient.JobOperations.GetJob("mybatchjob"); CloudTask myMultiInstanceTask = boundJob.GetTask("mymultiinstancetask"); // Now obtain the list of subtasks for the task IPagedEnumerable<SubtaskInformation> subtasks = myMultiInstanceTask.ListSubtasks(); // Asynchronously iterate over the subtasks and print their stdout and stderr // output if the subtask has completed await subtasks.ForEachAsync(async (subtask) => { Console.WriteLine("subtask: {0}", subtask.Id); Console.WriteLine("exit code: {0}", subtask.ExitCode); if (subtask.State == SubtaskState.Completed) { ComputeNode node = await batchClient.PoolOperations.GetComputeNodeAsync(subtask.ComputeNodeInformation.PoolId, subtask.ComputeNodeInformation.ComputeNodeId); NodeFile stdOutFile = await node.GetNodeFileAsync(subtask.ComputeNodeInformation.TaskRootDirectory + "\\" + Constants.StandardOutFileName); NodeFile stdErrFile = await node.GetNodeFileAsync(subtask.ComputeNodeInformation.TaskRootDirectory + "\\" + Constants.StandardErrorFileName); stdOut = await stdOutFile.ReadAsStringAsync(); stdErr = await stdErrFile.ReadAsStringAsync(); Console.WriteLine("node: {0}:", node.Id); Console.WriteLine("stdout.txt: {0}", stdOut); Console.WriteLine("stderr.txt: {0}", stdErr); } else { Console.WriteLine("\tSubtask {0} is in state {1}", subtask.Id, subtask.State); } });