Tasks and Threads don't run within static constructors in Linqpad

Question

This code waits indefinitely on the t.Wait() line.

void Main()
{
    Foo.Bar();
}

public static class Foo
{
    static Foo()
    {
        var t = Task.Factory.StartNew (() => 1);
        t.Wait();
        "Done".Dump();
    }

    public static void Bar()
    {
    }
}

I would expect the task to run and finish immediately. Any thoughts as to why? This doesn't seem to happen in instance constructors. v4.42.01

score 4 · Accepted Answer · edited May 23 '17 at 12:21

The "StartNew-and-Wait" part of your code works as expected (t.Result will be 1), if you put it into the Main or into the Bar method. It doesn't stop Wait-ing only if you put it into the static constructor, because "any operation that blocks the current thread in a static constructor potentially risks a deadlock".

In order to prevent executing static ctors multiple times concurrently, the CLR executes them under a lock. Here you try to call an anonymous method of Foo, and wait for it to finish, from the static ctor of Foo, which causes a deadlock.

Related SO pages: 1, 2

Tasks and Threads don't run within static constructors in Linqpad

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