React: [bug] Problems of using react-addons-perf

[joseph1125]

When trying to use [email protected] in Google Chrome, it is found that after Perf.start(), error messages displayed
Warning: There is an internal error in the React performance measurement code. Did not expect ctor timer to start while componentDidMount timer is still in progress for another instance.
Warning: There is an internal error in the React performance measurement code. We did not expect componentDidMount timer to stop while no timer is still in progress for another instance. Please report this as a bug in React.

After I typed Perf.stop() and try to use getWasted - this error message displayed
ReactPerf.js:239 Uncaught TypeError: Cannot read property 'updateCount' of undefined(…)

[aweary]

@joseph1125 can you share a JSFiddle reproducing the issue? You can use https://jsfiddle.net/reactjs/69z2wepo/ as a base.

[syranide]

6842

[gaearon]

Yeah, fairly sure this is a duplicate. The fix will be out in the next patch release.

[nathanmarks]

@gaearon What's the status of this in 15.2.0?

I'm getting results back from Perf.getWasted(measurements) but I'm seeing this warning crop up too:

Warning: There is an internal error in the React performance measurement code. We did not expect componentDidMount timer to stop while no timer is still in progress for another instance. Please report this as a bug in React.

Here is the code: https://gist.github.com/nathanmarks/a284a8c9a8c926bcd79c7a2a93427dbc

And here is a fiddle which reproduces the warning (same component above converted to createClass syntax):
https://jsfiddle.net/69z2wepo/47766/

[gaearon]

Interesting. Generally we haven't tested ReactPerf in this scenario much. It is primarily meant to be used from browser console, not from a wrapping component.

We should support this scenario better. If it's not fixed in 15.2.0 it's probably a bug. Can you send a PR that adds similar case as a failing test to ReactPerf-test? The test will fall if there is an expected warning so merely triggering this behavior should be enough.

[gaearon]

@nathanmarks Can you please check if your TimeWaster works after my change in #7202? You can clone React, run npm run build and then copy build/modules into your node_modules/react/lib to test the effect.

[nathanmarks]

@gaearon Looks good on my end, warning is gone. Awesome 👍

[gaearon]

I think all of the cases related to this should be solved in 15.2.1.
If not, please let me know with a case reproducing the issue.

[jdelafon]

I don't know if it is the same issue, but with 15.2.1 I just got

warning.js:44 Warning: There is an internal error in the React performance measurement code. Did not expect componentDidMount timer to start while render timer is still in progress for another instance. 

It happened after I added this minimal code to a working boilerplate kit:

import { Component, PropTypes } from 'react';

class Panel extends Component {
    render() {
        return <div>...</div>;
    }
}

export default Panel;

and added <Panel /> inside the render method of another pre-existing component.

Edit: it goes away when instead I use

import React from 'react';
.... React.Component {

But still the error is confusing.

[gaearon]

@jdelafon There’s a ton of code there. I would rather avoid spending 15 minutes setting it up just to discover I can’t reproduce the issue. Would you mind extracting the relevant part that produces the warning as a separate GitHub project or a JSFiddle so I could inspect it?

[faergeek]

This warning is also shown when something throws in render. I'm pretty sure that it's not intended behavior.

[faergeek]

Unfortunately I can't reproduce it with minimal case. Probably there's something wrong in my setup :-(

[gaearon]

Check if you have duplicate React in the bundle (maybe some component contains a copy in its own node_modules by mistake).

[shobhitg]

I experienced this issue first thing while trying out gaearon/todos:

There is an internal error in the React performance measurement code. Did not expect componentDidMount timer to start while render timer is still in progress for another instance.

[gelobelo02]

Experiencing this one too

 Warning: There is an internal error in the React performance measurement code. Did not expect componentDidMount timer to start while render timer is still in progress for another instance.

[jdelafon]

It is hard for us to isolate the problem without knowing where this warning comes from. It seems that ReactDebugTool is catching all kinds of errors, especially in render. It happens when there is really an error in my case, but it hides the real message. I don't have react-addons-perf in my package.json.

[gaearon]

It is hard for us to isolate the problem without knowing where this warning comes from. It seems that ReactDebugTool is catching all kinds of errors, especially in render.

There are no try-catch statements there. What likely happens is that you might have a Promise polyfill than doesn’t log its unhandled rejections. Therefore errors thrown inside render() get caught by that polyfill, and are never reported. Then React gets into an inconsistent state, and you see that warning (which is a symptom). But the real problem is the error thrown in your render() method, and you should make sure that whatever Promise polyfill you are using isn’t swallowing it.

I experienced this issue first thing while trying out gaearon/todos

Please provide exact steps to reproduce it. I cloned the project, ran npm install and npm start, and just don’t see any warnings.

---

To reiterate: I’m happy to reopen if this is a real issue but I can’t help without a project reproducing it.

[nathanmarks]

@gaearon I managed to reproduce it in gaearon/todos.

in src/components/VisibleTodoList.js, create a typo in mapStateToProps where getVisibleTodos() is called:

const mapStateToProps = (state) => {
  return {
    todos: getVisiblesTodos(state.todos, state.visibilityFilter), // typo creates a reference error
  };
};

Result:

warning.js:44 Warning: There is an internal error in the React performance measurement code. Did not expect componentDidMount timer to start while render timer is still in progress for another instance.warning
VisibleTodoList.js:36 Uncaught ReferenceError: getVisiblesTodos is not defined

[nathanmarks]

Just as an additional note -- I realise that this isn't hiding the message, but I personally haven't been able to reproduce this in a manner which completely hides the error message.

I haven't got this problem in my own application except when using HMR + react hot loader. In my own app, if I create a reference error in render and let it get hot reloaded, I get this error (HMR gives me the reference error). But if I do a complete refresh, I just see an unhandled in promise error in my console.

[nathanmarks]

Yeah, I'm not sure how to completely mask the error with this. By the way, is the perf tools warning intended to fire under these circumstances?

[gaearon]

@gaearon I managed to reproduce it in gaearon/todos.

This looks like correct behavior to me. The error is printed but it gets React into an inconsistent state.
We should probably rephrase to include something This might be caused by an error thrown in a component, in which case you should fix that error instead.

[gaearon]

Let’s reopen because we should definitely make this more user-friendly.
I’m open to suggestions here.

[nathanmarks]

Rephrasing is a good option. It's certainly correct behaviour given what happens, but the current message could be confusing to some.

One thing I haven't been able to reproduce is masking the original error. @jdelafon can you shed any light on how to reproduce this?

[jdelafon]

Apparently I did not notice the real error after the warning (I reproduced my example above and saw React is not defined after it). So it is fine, and rephrasing the warning should fix it.

[seanrucker]

Rephrasing seems like a good idea. I started seeing errors like this after upgrading to 15.2.1:

warning.js?8a56:44 Warning: There is an internal error in the React performance measurement code. Did not expect componentDidMount timer to start while render timer is still in progress for another instance.

I see now this is thrown anytime I have an error in one of my components (which happens frequently during development) but thought there was an additional problem due to the wording of the message.

[gaearon]

Got it. I think it was my mistake to enable this by default. We should change it to only be active in tests. I’ll get back to this soon.

[michaelsync]

I have the same error with 15.3.0 ..

Warning: There is an internal error in the React performance measurement code. Did not expect componentDidMount timer to start while render timer

[gaearon]

@michaelsync

Thanks for your comment, but this doesn’t help diagnose the issue in any way.
We already know that this warning exists.

Please read the comments above. There are two situations in which you can get this warning:

• Your application code throws an error, and this warning is just a byproduct. In this case, look for real error close to it. (I agree we should fix this case to not output a warning, it’s on my todo list.)
• There is an actual bug in React. In which case just saying you see this warning is not helpful. We will need to have an example reproducing it to fix the bug.

Thanks!

[tayiorbeii]

For anyone searching and finding this thread, I saw this warning when losing to a race condition arising from dispatching an async action in componentWillMount and trying to render before the data was available. Fixed it by adjusting my render logic.

[patrickgordon]

hey @tayiorbeii could you expand on this? I think I've got the same problem but not sure what I should be looking for...

[tayiorbeii]

Hey @patrickgordon, it's funny how long ago 9 days seems. I wish would I have been more clear in my previous comment. As I recall, my problem was along these lines:

const user = getUser(foo) || Map()
if (user) {
  // Stuff
}

The issue was I just looking at user being truthy and not having size > 0 (and therefore data from my call).

So in short, not a React issue. Look around your code for late night slip ups like that.

[gaearon]

Fixed via #7548. This will be out in the next release.

[gaearon]

Fixed in 15.3.2.