Documentation

Interacting with Batch Requests

You can use a BatchID string to ask the Cluster Manager for more information about the corresponding batch. Specifically, you can query the BatchStatus for that batch, and if the batch is complete you can retrieve the computed solution as a JSON string.

Your first step in using a BatchID to gather more information is to create a Gurobi environment that enables you to connect to your Cluster Manager. This is done in this line of our Python example:

    with setupbatchenv().start() as env, gp.Batch(batchID, env) as batch:

The setupbatchenv method creates an environment with the CSManager, UserName, and ServerPassword parameters set to appropriate values.

With this environment and our BatchID, we can now create a Batch object (by calling the Batch constructor in the above code segment) that holds information about the batch.

That Batch object can be used to query the BatchStatus:

    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()

It can also be used to perform various operations on the batch, including aborting or retrying the batch.

Once a batch has been completed, you can query the solution and all related attributes for tagged elements in the model by retrieving the associated JSON solution string (or by saving it into a file):

            print("JSON solution:")
            # Get JSON solution as string, create dict from it
            sol = json.loads(batch.getJSONSolution())

By default, the Cluster Manager will keep the solution for the model and other information for a while (the exact retention policy is set by the Cluster Manager). You can ask the Cluster Manager to discard information for a batch by explicitly calling the discard method:

        # Remove batch request from manager
        batch.discard()

No further queries on that batch are possible after this has been done.