Slow jobs block LS/RPC requests

[dbanck]

This is a followup from #1050

Background

A slow-running job will block an RPC request, leading to a bad UX and lagging/slow editor. One cause for a slow-running job might be an unstable/slow network connection.

@radeksimko discovered, that we track the job ID of the module registry job (which makes a network request):

terraform-ls/internal/indexer/document_change.go

Lines 109 to 122 in 055eaf9

	registryId, err := idx.jobStore.EnqueueJob(job.Job{
	Dir: modHandle,
	Func: func(ctx context.Context) error {
	return module.GetModuleDataFromRegistry(ctx, idx.registryClient,
	idx.modStore, idx.registryModStore, modHandle.Path())
	},
	Priority: job.LowPriority,
	Type: op.OpTypeGetModuleDataFromRegistry.String(),
	})
	if err != nil {
	return ids, err
	}
	ids = append(ids, registryId)

and wait for it to complete in the didOpen and didChange handlers:

terraform-ls/internal/langserver/handlers/did_change.go

Line 59 in 055eaf9

return svc.stateStore.JobStore.WaitForJobs(ctx, jobIds...)

terraform-ls/internal/langserver/handlers/did_open.go

Line 71 in 055eaf9

return svc.stateStore.JobStore.WaitForJobs(ctx, jobIds...)

This leads to blockage of the whole request until the network request is completed or timed out.

Terraform Configuration Files

terraform {
  required_providers {
    aws = {
      source = "hashicorp/aws"
    }
  }
}

module "eks" {
  source  = "terraform-aws-modules/eks/aws"
  version = "18.26.3"
}

Log Output

https://gist.github.com/dbanck/a097d77e27888bfd983412d3363c72e9

Expected Behavior

Requests should be processed fast and asynchronously

Actual Behavior

A slow job blocks the whole request and leads to suboptimal DX

Steps to Reproduce

Open the Terraform file in an editor and block/pause the language server network connections

Proposal

• We might not need to wait for all jobs to be complete, but only for those without external dependencies.
• In some instances (tests, performance reporting) we want to wait for all jobs

[dbanck]

I am closing this as #1258 resolves the slow networking requests.

The remaining work is tracked in #1056

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