User guide

Step 4: Determining the State of Your Spot Request
Next, we want to create code to wait until the Spot request reaches the "active" state before proceeding
to the last step. To determine the state of our Spot request, we poll the describeSpotInstanceRequests
method for the state of the Spot request ID we want to monitor.
The request ID created in Step 2 is embedded in the response to our requestSpotInstances request.
The following example code shows how to gather request IDs from the requestSpotInstances response
and use them to populate an ArrayList.
1 // Call the RequestSpotInstance API.
RequestSpotInstancesResult requestResult = ec2.requestSpotInstances(re
questRequest);
List<SpotInstanceRequest> requestResponses = requestResult.getSpotInstance
Requests();
5 // Setup an arraylist to collect all of the request ids we want to
// watch hit the running state.
ArrayList<String> spotInstanceRequestIds = new ArrayList<String>();
// Add all of the request ids to the hashset, so we can determine when they
hit the
10 // active state.
for (SpotInstanceRequest requestResponse : requestResponses) {
System.out.println("Created Spot Request: "+requestResponse.getSpotIn
stanceRequestId());
spotInstanceRequestIds.add(requestResponse.getSpotInstanceRequestId());
}
To monitor your request ID, call the describeSpotInstanceRequests method to determine the state
of the request. Then loop until the request is not in the "open" state. Note that we monitor for a state of
not "open", rather a state of, say, "active", because the request can go straight to "closed" if there is a
problem with your request arguments.The following code example provides the details of how to
accomplish this task.
1 // Create a variable that will track whether there are any
// requests still in the open state.
boolean anyOpen;
5 do {
// Create the describeRequest object with all of the request ids
// to monitor (e.g. that we started).
DescribeSpotInstanceRequestsRequest describeRequest = new DescribeSpot
InstanceRequestsRequest();
describeRequest.setSpotInstanceRequestIds(spotInstanceRequestIds);
10
// Initialize the anyOpen variable to false - which assumes there
// are no requests open unless we find one that is still open.
anyOpen=false;
15 try {
// Retrieve all of the requests we want to monitor.
DescribeSpotInstanceRequestsResult describeResult = ec2.describeS
potInstanceRequests(describeRequest);
List<SpotInstanceRequest> describeResponses = describeResult.get
SpotInstanceRequests();
Version v1.0.0
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AWS SDK for Java Developer Guide
Tutorial: Amazon EC2 Spot Instances