Support for Executing Multiple Tasks Sequentially or in Parallel

[x80486]

Running multiple tasks in Deno using the built-in task command is not quite flexible.

Would you consider the addition of a feature that allows users to execute multiple tasks sequentially or in parallel? I'm thinking about something like npm-run-all, so it's easier to define things like the following tasks without &&:

"tasks": {
  "format:check": "deno fmt --check",
  // lint
  // sync
  "test": "deno test",
  "verify": "deno --sequential format:check lint sync test"
}

[dsherret]

The current way to do this is:

"verify": "deno task format:check && deno task lint && deno task sync && deno task test"

Alternatively, in parallel, it's:

"verify": "deno task format:check & deno task lint & deno task sync & deno task test"

I'm not sure it's worth it to introduce another way of doing this.

[x80486]

I understand that you may not see immediate improvements. I created this issue to suggest a potentially more intuitive approach. My idea was to introduce options like --sequential and --parallel (from npm-run-all 😏) because I believe they convey the intended behavior more clearly while also reducing redundancy — we wouldn't have to write deno task for each.

This would offer a more user-friendly and straightforward way to achieve the desired task execution method.

[dsherret]

Tasks can accept CLI arguments (ex. deno task my_task arg1 arg2). I guess it would not be possible to provide arguments to an individual task with this approach?

[x80486]

Well, there are a few other platforms/tools that circumvent this by using --.

In this case, you could write something like: deno task --built-in-option-name -- taskName --task-option-name — where --built-in-option-name could be --run-parallel or --run-sequential, etc.

[johndeighan]

Regarding running tasks in parallel. My use case is to have 2 tasks, each of which watch for certain file changes. So, these 2 tasks each run forever, i.e. until you use Ctrl-C to kill them. But, if I understand the suggestion of using a task consisting of multiple tasks separated by &, the Ctrl-C would only kill one of the tasks. Is that correct?

[NfNitLoop]

As of Deno 2.1 (Nov. 21) we now have task dependencies! 🎉 And dependencies of a task get run in parallel automatically. ❤️

… unfortunately, this makes debugging things a bit more difficult.

• If I have a race condition with two of my task dependencies, it's difficult to test that out. (Would be nice if there were a --serial or -J1 option to limit task execution to a single task at a time!)

• If I have a task failure, it sometimes difficult to find which task failed. A --serial option would make sure that the Task [name] [command] header is properly interleaved between outputs. But it might also be nice just to have a failure footer like Task [name] failed when a task fails, so we know which one(s) to check.

[dsherret]

@NfNitLoop set DENO_JOBS=1 (https://docs.deno.com/runtime/reference/cli/task/#task-dependencies)

Also, opened #27647