C#C
C#•2y ago•
3 replies
Raki

Can anyone explain Bulkhead policy in polly

Can anyone explain Bulkhead policy in polly

I want to send API calls to an external API that only allows 10 calls per second. Therefore, I need my program to be limited to making only 10 HTTP calls per second. Additionally, if I encounter a 429 error (too many requests), I want to retry that call. I learned about the Bulkhead pattern from this article: https://medium.com/@ynskrn54/using-polly-and-the-bulkhead-pattern-in-net-f4a9639e2fcd, which helps in preventing overwhelming the external API.
I have written some code based on this pattern. My understanding is that this code will manage 10 calls at a time in a queue. For instance, if I have 30 HTTP calls to make, they will be queued and processed at a rate of 10 calls per second.
Is the below code serve my purpose
/Setting the policy
var bulkHeadPolicy = Policy.BulkheadAsync < HttpResponseMessage > (10, 1);

//Defining it in Startup.cs
services
  .AddHttpClient < IContentfulManagementService, ContentfulManagementService > ((s, c) => {
    c.BaseAddress = new Uri(managementApiURL);
    c.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", managementApiKey);
    c.Timeout = timeout;
  })
.AddTransientHttpErrorPolicy(ErrorPolicy) .AddPolicyHandler(timeoutPolicy).AddTransientHttpErrorPolicy(retryErrorPolicy).AddPolicyHandler(bulkHeadPolicy);

//Retry when it errors out
private static Func < PolicyBuilder < HttpResponseMessage > , IAsyncPolicy < HttpResponseMessage >> retryErrorPolicy =>
  p => p.Or < BulkheadRejectedException > ().WaitAndRetryAsync(3, retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)));
Medium
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