Weak pointers can lead to a space leak

[TeofilC]

This library creates a weak pointer with a finalizer each time that we attach a context to a thread that doesn't have a context.

This can lead to a space leak if we also detach contexts from threads manually (eg, using bracket). We end up with a situation where each time a new context is added, a new weak pointer is created. If the thread is long-lived then this can lead to a slow space leak.

I noticed this in a context where we had a long running job runner thread, which would acquire a new root span whenever it ran a job, and detached it afterwards.

I have just disabled the finalizer creation on our project for now, but I'd be interested to hear if you have a preferred solution.