Now if the reason for DNS change is failover, your connection would have been faulted anyway so this time connection would open against the new server. makes me wonder what kind of applications we build with. Internally in a myriad of PaaS offerings.Īnd this has been going on for more than 2 years without being reported. Everytime you change settings in your Azure Traffic Manager. So when does DNS change occur? Everytime you do blue-green deployment (in Azure cloud services when you deploy to staging slot and then swap production/staging slots). The main concern was thread safety when making concurrent HTTP calls - and even official documentations said there is no risk doing that.īut it turns out there is a serious issue: DNS changes are NOT honoured and HttpClient (through HttpClientHandler) hogs the connections until socket is closed.
In short, the community agreed that it was 100% safe, not only not disposing the HttpClient, but also to use it as Singleton. HttpClient implements IDisposable only indirectly through HttpMessageHandler and only as a result of in-case not an immediate need - I am not aware of an implementation of HttpMessageHandler that holds unmanaged resources (the mere reason for implementing IDisposable).
Singleton HttpClient matters, especially when it comes to the performance This lead to several discussions in the community ( here from Microsoft Patterns and Practices, Darrel Miller in here and a few references in StackOverflow here) to discuss whether it can be used with longer lifetime and more importantly whether it needs disposal.
Now, ironically it also implements IDisposable suggesting a short-lived lifetime and disposing it as soon as you are done with. Also you can plug in a CookieContainer to allow for all sessions. It conveniently allows for default headers to be set and applied to all requests. HttpClient is usually meant to be used with more than just a single request. HttpClient is a very nice and clean implementation that came as part of Web API and replaced its clunky predecessor WebClient (although only in its HTTP functionality, WebClient can do more than just HTTP). NET client-side app), you are very likely to be using an HttpClient. If you are consuming a Web API in your server-side code (or.
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