User-rate limit exceeded for GMail API using C# MCV

Question

Can anyone help me to get the solution User-rate limit exceeded for GMail API using C# MCV application. I am stuck with this since last 5 days. There was no document in internet. No solution from google also. I have billing enabled for access the google service. Using the code like...

var certificate = new X509Certificate2(AssemblyDirectory + string.Format("\\{0}",CertificateFileName), CertificatePassword, X509KeyStorageFlags.Exportable);

ServiceAccountCredential credential = new ServiceAccountCredential(new ServiceAccountCredential.Initializer(ServiceAccountEmail)
               {
                   Scopes = new[] { GmailService.Scope.GmailModify },
                   User=this.User
               }.FromCertificate(certificate));

 // Create the service.
 service = new GmailService(new BaseClientService.Initializer()
            {
                HttpClientInitializer = credential,
                ApplicationName = this.ApplicationName,
                ApiKey="xxxxxxxxxxxxxxxxxxx",
            }); 

ListLabelsResponse response = service.Users.Labels.List("me").Execute();
Labels = response.Labels.ToList();
if (!Labels.Select(l => l.Name).Contains("Processed"))
    {
         Labels.Add(CreateLabel("Processed"));
    }

Answer 1

Explanation

User-rate limit error messages are flood protection. The current user you are logged in as this being your service account can only make X number of requests a minute / second

As you can see the user can max make 25,000 queries in 100 seconds. Your application can make a max of 2,000,000 requests in 100 seconds. Gmail also has some other limits with recard to mail sending which have not been documented.

There is nothing you can do when you hit the user rate limit quota besides slow your application down.

Standard error messages

403: User Rate Limit Exceeded The per-user limit has been reached. This may be the limit from the Developer Console or a limit from the Drive backend.

{
 "error": {
  "errors": [
   {
    "domain": "usageLimits",
    "reason": "userRateLimitExceeded",
    "message": "User Rate Limit Exceeded"
   }
  ],
  "code": 403,
  "message": "User Rate Limit Exceeded"
 }
}

Suggested actions:

Use exponential backoff.

403: Rate Limit Exceeded The user has reached Google Drive API's maximum request rate. The limit varies depending on the kind of requests.

{
 "error": {
  "errors": [
   {
    "domain": "usageLimits",
    "message": "Rate Limit Exceeded",
    "reason": "rateLimitExceeded",
   }
  ],
  "code": 403,
  "message": "Rate Limit Exceeded"
 }
}

Suggested actions:

Use exponential backoff.

Implementing exponential backoff

Exponential backoff is a standard error handling strategy for network applications in which the client periodically retries a failed request over an increasing amount of time. If a high volume of requests or heavy network traffic causes the server to return errors, exponential backoff may be a good strategy for handling those errors. Conversely, it is not a relevant strategy for dealing with errors unrelated to rate-limiting, network volume or response times, such as invalid authorization credentials or file not found errors.

Used properly, exponential backoff increases the efficiency of bandwidth usage, reduces the number of requests required to get a successful response, and maximizes the throughput of requests in concurrent environments.

Create requests are not idempotent. A simple retry is insufficient and may result in duplicate entities. Check whether the entity exists before retrying.

Billing

It is not possible to increase the user rate limits they are there to keep developers from flooding Googles servers. Gmail API is free enabling billing isn't going to do much.

Note

TBH i would be surprised if you are getting this from doing a Users.Labels.List("me") unless you have this code running for every user hitting your website rather than caching the data.