Removed blocking call which was producing deadlocks from EC2Plugin.

[samunro]

The calls to Task.Result in GetToken and GetMetadata are blocking and can result in deadlocks if either the response or the timeout are handled on the same thread. See here for a similar example and explanation.

"Don’t block on Tasks; use async all the way down."
https://blog.stephencleary.com/2012/07/dont-block-on-async-code.html

One option here could have been to replace the calls to Result with the async and await keywords, but that would have required that modifications to the IPlugin interface and its consumers. That might be something that should be considered, but given that the call to Result was already making this code synchronous, nothing will be lost by using a synchronous API as an immediate fix.

There is a synchronous Send method which has been added to HttpClient in .Net 5 but it is not available in any of the targeted frameworks - .Net Framework 4.5, .Net Core 3.1 or .Net Standard 2.0.

Although HttpWebRequest is not recommended for new development, it does offer a synchronous alternative and is the option that I have used in this pull request.

"We don't recommend that you use HttpWebRequest for new development. Instead, use the System.Net.Http.HttpClient class."
https://docs.microsoft.com/en-us/dotnet/api/system.net.httpwebrequest?view=netframework-4.5

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[srprash]

Hi @samunro
Thanks for identifying this issue and providing the fix. We should switch to using async and await in our next major version bump.

[samunro]

Thanks @srprash. Are there any plans to release a new NuGet package? The last one was in April last year.

https://www.nuget.org/packages/AWSXRayRecorder.Core/

[srprash]

We are working on some operation stuff for our build system and plan to do the release which has been due for some time now. Thanks for your patience.