Error: cannot enable cancellation after promises are in use

Question

Error: cannot enable cancellation after promises are in use

mania25 opened this issue 8 years ago · 13 comments

Hi, i've got error message like this :

Please help to solve this, thank you

Answer 1 · 2017-05-01T16:25:20.000Z

Do you happen to use promises before loading this library i.e. require("node-telegram-bot-api")?

Answer 2 · 2017-05-31T13:35:57.000Z

I'm receiving exactly the same error message

Answer 3 · 2017-05-31T14:38:56.000Z

@dreadlocked Are you using promises before loading this library?

Answer 4 · 2017-06-12T19:32:46.000Z

I'm seeing the same error message, and yes I am using promises before loading the library. Is there a fix available?

Answer 5 · 2017-06-12T19:43:04.000Z

OK, so I see. This issue crops up if you are using bluebird in your app and you use a promise before requiring the telegram library. A simple solution is to do the following at the top of your app's entrypoint:

const Promise = require('bluebird');
Promise.config({
  cancellation: true
});

Answer 6 · 2017-06-22T09:16:08.000Z

I think the library should not configure promises. That should be something done by the host code (read: the library user). Such a fix would break backwards compatibility, thus will need to wait semver-major release.

However, we could allow the users to provide their preferred (and configured) promise library and work with that instead of the current default i.e. bluebird. We could then just drop bluebird and use native promises. *I smell a PR here 😉*

/cc @yagop

Answer 7 · 2017-06-27T17:29:22.000Z

I also think it's dangerous to opt-in to a configuration parameter such as this. Promise cancellation in bluebird affects the way that timeouts work.

One thing that's bitten me is the changing of how timeouts work when this config is enabled.

This is best explained with a code snippet.

const Promise = require('bluebird');

function prepare() {
  return new Promise((resolve, reject) => {
    setTimeout(() => resolve(), 2000);
  });
}

function build() {
  return prepare().then(() => console.log('it was built'));
}

function run() {
  return build()
    .timeout(1000)
    .catch(Promise.TimeoutError, err => console.log('there was an error'));
}

run();

When running the code above you will see:

there was an error
it was built

If you add the cancellation config, the 'it was built' log is never written. It seems that .timeout will cancel the underlying promise if this config param is set.

Needless to say, this has caused a lot of issues in my app that would be better resolved by not having this config set. 😄

Answer 8 · 2017-06-28T16:03:59.000Z

Update:

Deprecate auto-enabling of cancellation of Promises (commit 997393b)
Allow providing custom Promise constructor/library (commit c2902db)

Answer 9 · 2017-07-29T03:00:32.000Z

Maybe you guys will laugh, but simply requiring "node-telegram-bot-api" at the beggining of the app did the trick for me, i didn't even need to change anything on my app.

ie: app.coffee

P = require 'bluebird'
T = require 'node-telegram-bot-api'

# rest of my app now works perfectly

Answer 10 · 2017-08-24T16:38:14.000Z

Is your update not yet merged to master? @GochoMugo
Because i still experiencing this issue

Answer 11 · 2017-08-25T15:15:25.000Z

@hems Yes. require()ing the library before using any promises works around this bug.

@setyongr We just deprecated this. Let me deliver a proper fix for this.

Answer 12 · 2017-08-25T15:59:53.000Z

Conclusion:

Automatic enabling of Promise cancellation has been deprecated.
Temporary fix : load/require() the library, as early as possible, before using any Promises.
Permanent fix: set the environment variable NTBA_FIX_319 (to any value). You will have to enable Promise cancellation yourself, if you need it. This fix will be applied by default once we bump major version as it introduces backwards-incompatible changes.
This issue has been locked to ensure that this message reaches anyone who might stumble upon it. If necessary, please create a new issue.
This issue will be closed once we hit v1.

Answer 13 · 2022-07-18T13:24:36.000Z

Fix on the next release. Remove bluebird and use native promises