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我想在新用戶到達時創建ec2實例。我創建了一個servlet類來執行此操作。當用戶到達時，我檢查DB是新用戶還是不新用戶，然後創建實例併發回他/她的IP。當我向用戶發送http請求到這個servlet一個接一個，我正確地得到IP。但是，當我並行發送HTTP調用（對於user1發送請求在tab1中，對於user2同時發送請求在tab2中獲得來自user1 HTTP調用的響應之前）。當我這樣做時，我得到了錯誤。有時USER1說AWS EC2實例：啓動多個實例
「實例ID 'I-0b79495934c3b5459' 不存在（服務： AmazonEC2;狀態代碼：400;錯誤代碼：InvalidInstanceID.NotFound; 請求ID：e18a9eaa-cb1b-4130-a3ee -bf1b19fa184c）「
並且user2發送IP作爲響應。請幫助我解決問題的方法和方法。 這是我創建的Servlet類。
public class GateKeeperController extends HttpServlet {
private static final long serialVersionUID = 1L;
BasicAWSCredentials awsCreds = new BasicAWSCredentials(credentials);
AmazonEC2Client ec2Client = new AmazonEC2Client(awsCreds);
RunInstancesRequest runInstancesRequest;
RunInstancesResult runInstancesResult;
Reservation reservation;
Instance intstance;
DescribeInstancesRequest describeInstanceRequest;
DescribeInstancesResult describeInstanceResult;
GatekeeperModal gateKeepermodal;
String sourceAMI = null;
String destinationAMI = null;
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
HttpSession s = request.getSession();
String userID = (String) request.getParameter("userID");
Double lattitude = Double.parseDouble((String) request.getParameter("lat"));
Double lonitude = Double.parseDouble((String) request.getParameter("long"));
if (userID != null) {
Pair coordinates = new Pair(lattitude, lonitude);
RegionSelection targetRegion = new RegionSelection();
String regionResult = targetRegion.getRegion(coordinates);
String instanceIP = null;
gateKeepermodal = new GatekeeperModal();
try {
if (gateKeepermodal.checkUserIsNew(userID)) {
instanceIP = startInstance(userID, regionResult);
if (instanceIP != null) {
response.getWriter().write(instanceIP);
}
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else {
}
}
private String startInstance(String userID, String region) {
String ami_id = new AMI().getAMI_ID(region);
ec2Client.setEndpoint(region);
runInstancesRequest = new RunInstancesRequest();
runInstancesRequest.withImageId(ami_id).withInstanceType("t2.micro").withMinCount(1).withMaxCount(1)
.withKeyName("GateKeeper_User").withSecurityGroups("GateKeeper User");
runInstancesResult = ec2Client.runInstances(runInstancesRequest);
reservation = runInstancesResult.getReservation();
intstance = reservation.getInstances().get(0);
String s1 = intstance.getState().getName();
String s2 = InstanceStateName.Running.name();
while (!s1.toLowerCase().equals(s2.toLowerCase())) {
describeInstanceRequest = new DescribeInstancesRequest();
describeInstanceRequest.withInstanceIds(intstance.getInstanceId());
ec2Client.setEndpoint(region);
describeInstanceResult = ec2Client.describeInstances(describeInstanceRequest);
reservation = describeInstanceResult.getReservations().get(0);
intstance = reservation.getInstances().get(0);
s1 = intstance.getState().getName();
s2 = InstanceStateName.Running.name();
}
GateKeeperUser user = new GateKeeperUser(userID, intstance.getInstanceId(), intstance.getPublicIpAddress(),
region);
Boolean result;
try {
result = gateKeepermodal.createUser(user);
if (result) {
return intstance.getPublicIpAddress();
} else {
return null;
}
} catch (SQLException e) {
}
return null;
}
}