fix(WorkerPool): trace stacks to avoid duplicated `err.messages` from workers #13

sendilkumarn · 2018-01-19T00:04:09Z

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jsf-clabot · 2018-01-19T00:04:10Z

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Codecov Report

Merging #13 into master will not change coverage.
The diff coverage is 0%.

@@         Coverage Diff          @@
##           master   #13   +/-   ##
====================================
  Coverage       0%    0%           
====================================
  Files           6     7    +1     
  Lines         359   371   +12     
  Branches       63    64    +1     
====================================
- Misses        314   325   +11     
- Partials       45    46    +1

Impacted Files	Coverage Δ
src/WorkerError.js	`0% <0%> (ø)`
src/WorkerPool.js	`0% <0%> (ø)`	⬆️

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michael-ciniawsky

@sendilkumarn Could you post a screenshot of current output you get (for reference) ?

michael-ciniawsky · 2018-01-19T11:59:43Z

src/WorkerPool.js


 class PoolWorker {
  constructor(options, onJobDone) {
+    this.options = options;


Is this needed or would using options directly also be sufficient ?

I feel this is better and aligns to the style

michael-ciniawsky · 2018-01-19T12:07:56Z

src/WorkerPool.js

    err.message = obj.message;
    if (obj.stack) {
-      err.stack = `${obj.stack}\n\tfrom thread-loader (worker ${this.id})\n${err.stack}`;
+      let additionalStack = '';


err.stack = `${obj.stack}\n\nThread Loader (Worker ${this.id})` if (this.options.stack) { // Limit the err.stack manually in case stackTraces are to verbose if (typeof options.stack === 'number') Error.stackTraceLimit(options.stack) } err.stack += `\n\n${err.stack}` } else { // Only the err.message const message = (stack) => stack.split('\n')[0] err.stack += `\n\n${message(err.stack)}` }

I like this idea. the stacktraceLimit is not a function but fairly. I will change the implementation.

sendilkumarn · 2018-01-19T12:16:27Z

This one.

michael-ciniawsky · 2018-01-19T12:19:11Z

hmm.. this looks like a duplicate of obj.stack to some point. Is this often the case ?

sendilkumarn · 2018-01-19T12:31:57Z

Yes in terms of create-react-app (& mostly when I test it manually) (but I haven't done extensive research on various other applications) (let me know if there is any that I can check out)

michael-ciniawsky · 2018-01-19T12:41:47Z

I also don't have enough knowledge about the {Error} handling here and if outputting the obj.stack would be enough. There most be a reason for adding an additional err.stack, but we should investigate this :)

michael-ciniawsky

What does the output for

`{Boolean}`

{ stack: false )

`{Number}`

{ stack: 5 } // for e.g

look like now ?

sendilkumarn · 2018-01-19T15:42:50Z

Both are same. But when I increase the number to say 10 (default for stack trace) Then I see those many lines

gaearon · 2018-01-19T18:24:42Z

src/WorkerPool.js

+      if (this.options.stack) {
+        // Limit the err.stack manually in case stackTraces are to verbose
+        if (typeof this.options.stack === 'number') {
+          Error.stackTraceLimit = (this.options.stack);


Is this setting a global? It seems very non-intuitive to have a package set global configuration like this.

good one. But I dont think this will have a global impact. But @michael-ciniawsky would be correct one to answer

You're setting it on a global so I don't see how it could be local.
From the docs (https://nodejs.org/api/errors.html#errors_error_stacktracelimit):

Changes will affect any stack trace captured after the value has been changed.

But it changes the value in a worker thread. ( well I may be totally wrong) I will check this

This is the code that rethrows the error from the worker so it runs in the main thread.
I suggested another solution below.

gaearon · 2018-01-19T18:31:37Z

OK, so the problem here is that .stack property on Node includes not just the stack trace, but also the message itself.

The original intention was probably to preserve both stacks:

the original error stack from the thread
the rethrown stack

Both could be valuable depending on what exactly you're debugging (where the error actually happened vs how it "occurred" into your app). So I'd vote to keep both but cut away the duplicate message.

I propose to:

Take obj.stack.
Add From worker: and err.stack to it but first slice only the part after err.message.

Then we'll get both stacks but the message won't be duplicated.

gaearon

Why do we need this option at all?

Do you have any reservations about my earlier suggestion?

sendilkumarn · 2018-01-21T01:30:02Z

err.stack to it but first slice only the part after err.message.

index.js:2178 ./src/App.js
Syntax error: /awesomemac/create-react-app/awesome-app-1/src/App.js: Unexpected token, expected "{" (6:10)

  4 | 
  5 | class App extends Component {
> 6 |   render()) {
    |           ^
  7 |     return (
  8 |       <div className="App">
  9 |         <header className="App-header">
	Thread Loader (Worker 2)
4 | 
  5 | class App extends Component {
> 6 |   render()) {
    |           ^
  7 |     return (
  8 |       <div className="App">
  9 |         <header className="App-header">
	Thread Loader (Worker 2)

This will be the output. If we have just removed the message from err.

Since we are reconstructing the error with the same object. Mostly both of the stack remains the same.

I am not convinced to add the same information again

gaearon · 2018-01-21T01:47:07Z

This will be the output. If we have just removed the message from err.

I don't understand why. Clearly the code frame is identical in your example. The code frame is part of the message. Therefore, if it was not "cut off", the problem is with the code that cuts it off.

I'm not saying my exact algorithm is correct. But hopefully you can see that the .message is the same between two errors, and therefore there should be a way to just cut off the right part from the second .stack property :-)

sendilkumarn · 2018-01-21T01:52:18Z

The code frame is part of the message. Therefore, if it was not "cut off", the problem is with the code that cuts it off.

Interestingly both message and stack is same in both the cases

sendilkumarn · 2018-01-21T01:54:02Z

const err = new Error(obj.message);

Doesn't it wrap and throw the same error 🤔 Ideally when you run this, they should be equal right

michael-ciniawsky · 2018-01-22T21:19:15Z

Maybe worth a try

const err = new Error('I\'m an Error')
const stack = err.stack.split('\n').filter((line) => line.includes('at'))
console.log(stack)

const worker = (err) => {
  return new Error(err)
}

const err2 = worker(err)
const stack2 = err2.stack.split('\n').filter((line) => line.includes('at'))
console.log(stack2)

const length = stack2.length - stack.length

const result = stack2.slice(0, length).join('\n')
console.log(result) // at worker (/Users/User/path/to/index.js:6:10)

// ${obj.stack}
//
// Thread Loader (Worker 1)
//
// at worker (/Users/User/path/to/index.js:6:10)

sendilkumarn · 2018-01-22T22:27:36Z

Error screen shot as of now

sendilkumarn · 2018-01-22T22:31:44Z

@michael-ciniawsky As I said in the above comment

yes they are literally the same, except for the first line which says that the error is thrown from that corresponding statement's line number. Apart from that everything is same.

gaearon · 2018-01-22T23:28:20Z

@michael-ciniawsky Would you mind keeping Thread Loader prefixed with at like other lines in the stack trace? That would make it more convenient for tools that automatically filter out stack traces with regular expressions.

michael-ciniawsky · 2018-01-23T00:32:29Z

const stack = (origin, worker) => {
  origin = origin
    .split('\n')
    .filter((line) => line.includes('at'))

  worker = worker
    .split('\n')
    .filter((line) => line.includes('at'))
    .map((line) => `${line} [Thread Loader (Worker 1)]`) // needs to be replaced with `${id}`

  const diff = worker.slice(0, worker.length - origin.length).join('\n')

  origin.unshift(diff)

  return origin.join('\n')
}

class WorkerError extends Error {
  constructor (err) {
    super(err)

    this.name = err.name
    this.message = err.message

    Error.captureStackTrace(this, this.constructor)

    this.stack = stack(err.stack, this.stack)
  }
}

const err = new Error('I\'m an Error')

const worker = (err) => {
  throw new WorkerError(err)
}

console.log(worker(err))

  throw new WorkerError(err)
  ^

    at worker (/Users/User/path/to/index.js:34:9) [Thread Loader (Worker 1)] // <=
    at Object.<anonymous> (/Users/Cini/DEV/JS/index.js:31:13)
    at Module._compile (module.js:641:30)
    at Object.Module._extensions..js (module.js:652:10)
    at Module.load (module.js:560:32)
    at tryModuleLoad (module.js:503:12)
    at Function.Module._load (module.js:495:3)
    at Function.Module.runMain (module.js:682:10)
    at startup (bootstrap_node.js:191:16)
    at bootstrap_node.js:613:3

michael-ciniawsky · 2018-01-23T00:37:42Z

@gaearon Yep, the from thread-loader notice if within the stack should definitely align with 'standard' stack formatting

gaearon · 2018-01-23T00:37:56Z

line.includes('at')

is too broad.

For example,

throw new Error('There was a problem at MyComponent definition.');

will incorrectly match the first line (the message) as being part of the stack trace.

This is why in my suggestion in #13 (comment) I search for first end of the message inside the stack. That's guaranteed to be where the real stack trace starts.

michael-ciniawsky · 2018-01-23T00:44:31Z

I just used it includes while prototyping, use a {RegExp}, Array.prototype.indexOf etc to make it bullet proofen 😛

gaearon · 2018-01-23T00:46:16Z

My point is you can’t really reliably match the stack trace without knowing the message.

For all we know, at ... could be a part of the message (e.g. if somebody else manipulates it the same way). We don't want to throw that away.

The only reliable way to know when the real stack trace starts is to check where the message ends inside of it.

(Sorry if I misunderstood and you agree with this point. I’m stressing it because it seems important for correctness.)

michael-ciniawsky · 2018-01-23T01:26:59Z

/^(\s+at\s.+\s\(.+\))/.test(line)

But the diffing is already advanced anyways, replacing the stack with the updated one from the worker and maybe prepending e.g Thread Loader [Worker ${id}] as title to the err.message should do the job aswell as long as there aren't duplicates anymore :)

Thread Loader [Worker ${id}] // prepend

// 'Original'
${err.message}
${err.frame}

${worker.stack} // update

sendilkumarn · 2018-01-30T06:37:45Z

@michael-ciniawsky but there are duplicates.

worker.stack contains err.message in it. that causes the duplication.

michael-ciniawsky · 2018-02-05T23:12:40Z

worker.stack contains err.message in it. that causes the duplication.

Just remove the err.message from the worker.stack ? :)

gaearon · 2018-02-05T23:14:54Z

I think that’s what my code in #13 (comment) was doing?

michael-ciniawsky · 2018-02-05T23:27:47Z

  fromErrorObj (arg) {
    let obj;

    if (typeof arg === 'string') {
      obj = { message: arg };
    } else {
      obj = arg;
    }
-    const err = new Error(obj.message);
+   return new WorkerError(obj);
-    err.message = obj.message;
-    if (obj.stack) {
-      const trim = (error) => {
-        const { stack, message } = error;
-        const trace = stack.indexOf(message) + message.length;
-        return stack.substr(trace);
-      };

-      err.stack = `${obj.stack}\nThread Loader (Worker ${this.id})\n\n${trim(err)}`;-
-    }
-    err.hideStack = obj.hideStack;
-    err.details = obj.details;
-    return err;
  }

class WorkerError extends Error {
    constructor (obj) {
       // ...format the original {Error}
    }
}

export default WorkerError

`WorkerError Format (Suggestion)`

Thread Loader (Worker ${id})

<Original Message (err.message)>

<Worker Stack>

Is all I'm asking and it's 95% done already :)

gaearon · 2018-02-05T23:35:16Z

Ah okay I see what you mean now 🤗

@sendilkumarn Mind extracting?

michael-ciniawsky

@sendilkumarn Thx

Can you show a screenshot how it this looks like now please :) ?

sendilkumarn · 2018-02-07T15:15:44Z

Thread Loader (Worker 1)
I'm an Error
    at worker (/Users/sendilkumar/Dev/thread-loader/index.js:6:9)
    at Object.<anonymous> (/Users/sendilkumar/Dev/thread-loader/index.js:3:13)
    at Module._compile (module.js:660:30)
    at Object.Module._extensions..js (module.js:671:10)
    at Module.load (module.js:573:32)
    at tryModuleLoad (module.js:513:12)
    at Function.Module._load (module.js:505:3)
    at Function.Module.runMain (module.js:701:10)
    at startup (bootstrap_node.js:193:16)
    at bootstrap_node.js:617:3

alexander-akait

Why need package-lock.json for this?

sendilkumarn · 2018-02-07T15:29:09Z

@evilebottnawi reverted

alexander-akait · 2018-02-07T15:33:20Z

@sendilkumarn good work! Thanks!

michael-ciniawsky · 2018-02-21T20:50:39Z

Released in v1.1.3 🎉 Sry for the delay here

sendilkumarn force-pushed the option-stack branch from 2a06d3c to ddd6c44 Compare January 19, 2018 00:14

sendilkumarn changed the title ~~Adding addtional option stack to control the stack when there is an erroe~~ Adding addtional option stack to control the stack when there is an error Jan 19, 2018

Adding addtional option stack to control the stack

c78364e

sendilkumarn force-pushed the option-stack branch from ddd6c44 to c78364e Compare January 19, 2018 00:24

michael-ciniawsky suggested changes Jan 19, 2018

View reviewed changes

alexander-akait added type: Feature priority: 5 (nice to have) pr_action: Review semver: Minor labels Jan 19, 2018

alexander-akait added this to the 1.2.0 milestone Jan 19, 2018

alexander-akait requested review from alexander-akait and joshwiens January 19, 2018 12:14

michael-ciniawsky changed the title ~~Adding addtional option stack to control the stack when there is an error~~ feat: add option to control stack trace formatting (options.stack) Jan 19, 2018

revamping the stack trace with more better options

23c884e

michael-ciniawsky reviewed Jan 19, 2018

View reviewed changes

gaearon reviewed Jan 19, 2018

View reviewed changes

making the stack to false by default

0589078

gaearon reviewed Jan 21, 2018

View reviewed changes

fixing the review comments

111ed75

sendilkumarn added 2 commits February 7, 2018 14:57

moving the error into workererror

62f4871

handling trim

a2f3c19

michael-ciniawsky approved these changes Feb 7, 2018

View reviewed changes

alexander-akait requested changes Feb 7, 2018

View reviewed changes

revert package-lock file

ce61e12

michael-ciniawsky merged commit 80dda4f into webpack:master Feb 7, 2018

michael-ciniawsky added status: Approved and removed pr_action: Review priority: 5 (nice to have) labels Feb 7, 2018

michael-ciniawsky removed this from the 1.1.4 milestone Feb 9, 2018

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fix(WorkerPool): trace stacks to avoid duplicated err.messages from workers #13

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{Boolean}

{Number}

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fix(WorkerPool): trace stacks to avoid duplicated `err.messages` from workers #13

fix(WorkerPool): trace stacks to avoid duplicated `err.messages` from workers #13

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`{Boolean}`

`{Number}`

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