The `nodejs` language support is implemented as two programs: one that
manages the initial connection to the engine and provides the language
serivce itself, and another that the language service invokes in order
to run a `nodejs` Pulumi program. The latter is responsible for running
the user's program and communicating its resource requests to the
engine. Currently, `run` effectively assumes that the user's program
will run synchronously from start to finish, and will disconnect from
the engine once the user's program has completed. This assumption breaks
if the user's program requires multiple turns of the event loop to
finish its root resource requests. For example, the following program
would fail to create its second resource because the engine will be
disconnected once it reaches its `await`:
```
(async () => {
let a = new Resource();
await somePromise();
let = new Resource();
})();
```
These changes fix this issue by disconnecting from the engine during
process shutdown rather than after the user's program has finished its
first turn through the event loop.
A dynamic resource is a resource whose provider is implemented alongside
the resource itself. This provider may close over and use orther
resources in the implementation of its CRUD operations. The provider
itself must be stateless, as each CRUD operation for a particular
dynamic resource type may use an independent instance of the provider.
Changes to the definition of a resource's provider result in replacement
of the resource itself (rather than a simple update), as this allows the
old provider definition to delete the old resource and the new provider
definition to create an appropriate replacement.
