Concurrency issue when initializing JS engine switcher in startup about javascriptengineswitcher HOT 4 CLOSED

We are not using the JavaScript Engine Switcher directly our self, only configuring it. It is being used by LigerShark.WebOptimizer.Sass (or more precisely, one of its dependencies).

Thanks for information! I have an idea how to prevent this error.

from javascriptengineswitcher.

Hello, Ville!

I tried to solve this problem in JavaScript Engine Switcher 3.24.0 and WebOptimizer.Sass 3.0.115. You need to add the following setting to the Startup.cs file:

…
public void ConfigureServices(IServiceCollection services)
{
    …
    // Registration of JS engines
    services.AddJsEngineSwitcher(options =>
    {
        options.AllowCurrentProperty = false;
        options.DefaultEngineName = JintJsEngine.EngineName;
    })
        .AddJint()
        ;
    …

In this case, AllowCurrentProperty property forbid access to the JsEngineSwitcher.Current property, and thus all work is done through standard ASP.NET Core DI.

from javascriptengineswitcher.

Hello, Ville!

It is assumed that registration of engines in the JavaScript Engine Switcher is performed only once at start of the application (for example, in regular tests I use a special initializer). Under normal conditions, methods of the Startup class are also called only once when the application starts. Perhaps this behavior changes when using a WebApplicationFactory and because of this the error occurs.

Internally, registration of engines in the JavaScript Engine Switcher is based not on the IServiceCollection interface, but on the JsEngineSwitcher.Current property. In fact, JavaScript Engine Switcher is a global variable. This implementation is due to the fact that this library was created before appeared .NET Core and is still used in a large number of projects written in .NET Framework.

Are you directly using a JavaScript Engine Switcher or using some library that uses it as a dependency?

from javascriptengineswitcher.

We are not using the JavaScript Engine Switcher directly our self, only configuring it. It is being used by LigerShark.WebOptimizer.Sass (or more precisely, one of its dependencies).

Now that I think about it, we do not need to compile the sass in our tests and thus there should not be any need to configure JavaScript Engine Switcher in tests.

I'm closing this issue as this is not common/supported case and there are many easy ways to circumvent the problem.

Thanks for all the work you do with this library!

from javascriptengineswitcher.