Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

module: handle Top-Level Await non-fulfills better #34640

Closed
wants to merge 3 commits into from

Conversation

addaleax
Copy link
Member

@addaleax addaleax commented Aug 6, 2020

Handle situations in which the main Promise from a TLA module
is not fulfilled better:

  • When not resolving the Promise at all, set a non-zero exit code
    (unless another one has been requested explicitly) to distinguish
    the result from a successful completion.
  • When rejecting the Promise, always treat it like an uncaught
    exception. In particular, this also ensures a non-zero exit code.

Refs: #34558


I’m sorry, this is a bit late. I’ve added the dont-land label on #34558 – I remember these points being brought up before in discussion (not sure where), but it seems like they weren’t revisited before unflagging TLA on master. I personally think they need to be addressed before we actually ship this, and in particular silently treating await unresolved or await rejected as a success is not acceptable.

@MylesBorins @nodejs/modules-active-members

Checklist
  • make -j4 test (UNIX), or vcbuild test (Windows) passes
  • tests and/or benchmarks are included
  • documentation is changed or added
  • commit message follows commit guidelines

Handle situations in which the main `Promise` from a TLA module
is not fulfilled better:

- When not resolving the `Promise` at all, set a non-zero exit code
  (unless another one has been requested explicitly) to distinguish
  the result from a successful completion.
- When rejecting the `Promise`, always treat it like an uncaught
  exception. In particular, this also ensures a non-zero exit code.

Refs: nodejs#34558
@nodejs-github-bot nodejs-github-bot added the process Issues and PRs related to the process subsystem. label Aug 6, 2020
@addaleax addaleax added esm Issues and PRs related to the ECMAScript Modules implementation. request-ci Add this label to start a Jenkins CI on a PR. labels Aug 6, 2020
@MylesBorins
Copy link
Contributor

@addaleax if this PR lands would you feel like the questions are resolved or are there still things we need to sort out?

@addaleax
Copy link
Member Author

addaleax commented Aug 6, 2020

@MylesBorins In my very subjective opinion, this PR would bring things where they need to be. ;)

@github-actions github-actions bot removed the request-ci Add this label to start a Jenkins CI on a PR. label Aug 6, 2020
@nodejs-github-bot
Copy link
Collaborator

@@ -2588,6 +2588,8 @@ cases:
and generally can only happen during development of Node.js itself.
* `12` **Invalid Debug Argument**: The `--inspect` and/or `--inspect-brk`
options were set, but the port number chosen was invalid or unavailable.
* `13` **Unfinished Top-Level Await**: `await` was used outside of a function
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

this will be used if any part of the import() process stalls, for example a loader returning a promise that never resolves.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Are you suggesting to explicitly list that special case? I would prefer not to, if you’re working on an ESM loader then you can probably imagine that import() stalling would look like unfinished TLA. The far more common case is going to be actual TLA usage, I assume

Copy link
Member

@devsnek devsnek Aug 6, 2020

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

No I'm just saying, with the current implementation, 13 doesn't actually imply the lack of promise resolution came from a source text module with TLA. I think the best we could do is moving the exitCode check to where module.evaluate() is called, although that still isn't inherently a source text module using TLA.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

To be clear, I consider any kind of failure to finish the main module’s evaluation, whether through TLA or not, something that should not be considered a successful operation. This is intentional, and I would be against restricting the check here to only module.evaluate().

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I agree we shouldn't consider those success cases. I'm saying, the message says "Unfinished Top-Level Await" but it can be caused by other things, which is potentially confusing. It might be better to rename it to "ESM Import Stalled" or something and mention that while many things can cause it, it would probably be caused by await (promise that never resolves)

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I don’t think most people would know what “ESM Import Stalled” means.

Again, I think this is mostly relevant when you’re actually developing a loader or similar, and in that case you most likely don’t even need any explanation at all.

Copy link

@bricss bricss Aug 6, 2020

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

IMO, Stalled Top-Level Await will be the best mix of both 🙄

@MylesBorins MylesBorins added the request-ci Add this label to start a Jenkins CI on a PR. label Aug 6, 2020
@github-actions github-actions bot removed the request-ci Add this label to start a Jenkins CI on a PR. label Aug 6, 2020
@nodejs-github-bot
Copy link
Collaborator

nodejs-github-bot commented Aug 6, 2020

Copy link
Contributor

@MylesBorins MylesBorins left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

RSLGTM

@addaleax addaleax added the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label Aug 6, 2020
@MylesBorins
Copy link
Contributor

If no one objects I plan to land this right at the 48 hour mark so we can unblock TLA for 14.8.0

addaleax added a commit that referenced this pull request Aug 8, 2020
Handle situations in which the main `Promise` from a TLA module
is not fulfilled better:

- When not resolving the `Promise` at all, set a non-zero exit code
  (unless another one has been requested explicitly) to distinguish
  the result from a successful completion.
- When rejecting the `Promise`, always treat it like an uncaught
  exception. In particular, this also ensures a non-zero exit code.

Refs: #34558

PR-URL: #34640
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Guy Bedford <[email protected]>
Reviewed-By: Myles Borins <[email protected]>
Reviewed-By: Yongsheng Zhang <[email protected]>
@addaleax
Copy link
Member Author

addaleax commented Aug 8, 2020

Landed in e948ef3

@addaleax addaleax closed this Aug 8, 2020
@addaleax addaleax deleted the esm-tla-fixes branch August 8, 2020 18:34
addaleax added a commit that referenced this pull request Aug 8, 2020
Handle situations in which the main `Promise` from a TLA module
is not fulfilled better:

- When not resolving the `Promise` at all, set a non-zero exit code
  (unless another one has been requested explicitly) to distinguish
  the result from a successful completion.
- When rejecting the `Promise`, always treat it like an uncaught
  exception. In particular, this also ensures a non-zero exit code.

Refs: #34558

PR-URL: #34640
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Guy Bedford <[email protected]>
Reviewed-By: Myles Borins <[email protected]>
Reviewed-By: Yongsheng Zhang <[email protected]>
@codebytere codebytere mentioned this pull request Aug 10, 2020
codebytere pushed a commit that referenced this pull request Aug 11, 2020
Handle situations in which the main `Promise` from a TLA module
is not fulfilled better:

- When not resolving the `Promise` at all, set a non-zero exit code
  (unless another one has been requested explicitly) to distinguish
  the result from a successful completion.
- When rejecting the `Promise`, always treat it like an uncaught
  exception. In particular, this also ensures a non-zero exit code.

Refs: #34558

PR-URL: #34640
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Guy Bedford <[email protected]>
Reviewed-By: Myles Borins <[email protected]>
Reviewed-By: Yongsheng Zhang <[email protected]>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
author ready PRs that have at least one approval, no pending requests for changes, and a CI started. esm Issues and PRs related to the ECMAScript Modules implementation. process Issues and PRs related to the process subsystem.
Projects
None yet
Development

Successfully merging this pull request may close these issues.

8 participants