search

AndreasMadsen / trace

Creates super long stack traces
https://trace.js.org
MIT License
194 stars 18 forks source link

The dreaded "throwing after await" #34

Open fasterthanlime opened 7 years ago

fasterthanlime commented 7 years ago

This might be completely expected, I'm not completely up-to-date on the state of node.js, but:

Repro steps

git clone https://github.com/fasterthanlime/async-test && cd async-test
npm i
npm start

Versions

$ node --version
v8.0.0

$ npm list
async-test@1.0.0 C:\msys64\home\amwenger\Dev\async-test
`-- trace@3.0.0
  `-- stack-chain@1.3.7

Output

=================================
 Throwing first thing
=================================
Full stack trace:
Error: throwing first thing
    at cherrypie (C:\msys64\home\amwenger\Dev\async-test\index.js:12:13)
    at binomial (C:\msys64\home\amwenger\Dev\async-test\index.js:14:40)
    at abacus (C:\msys64\home\amwenger\Dev\async-test\index.js:15:38)
    at main (C:\msys64\home\amwenger\Dev\async-test\index.js:16:22)
    at Object.<anonymous> (C:\msys64\home\amwenger\Dev\async-test\index.js:34:1)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at <anonymous>
    at checkStack (C:\msys64\home\amwenger\Dev\async-test\index.js:38:5)
    at main (C:\msys64\home\amwenger\Dev\async-test\index.js:16:11)
    at Object.<anonymous> (C:\msys64\home\amwenger\Dev\async-test\index.js:34:1)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3

=================================
 Throwing after await
=================================
Full stack trace:
Error: after timeout
    at cherrypie (C:\msys64\home\amwenger\Dev\async-test\index.js:26:13)
    at <anonymous>
    at <anonymous>
    at checkStack (C:\msys64\home\amwenger\Dev\async-test\index.js:38:5)
    at main (C:\msys64\home\amwenger\Dev\async-test\index.js:30:11)
    at <anonymous>
    at runMicrotasksCallback (internal/process/next_tick.js:86:5)
    at _combinedTickCallback (internal/process/next_tick.js:95:7)
    at process._tickCallback (internal/process/next_tick.js:161:9)
    at Function.Module.runMain (module.js:607:11)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3

didn't see abacus, bailing

Expected output

In the second trace, something like:

<snip>
Error: after timeout
    at cherrypie (C:\msys64\home\amwenger\Dev\async-test\index.js:26:13)
    at binomial (path:line)
    at abacus (path:line)
<snip>
fasterthanlime commented 7 years ago

N.B: turning

const binomial = async () => await cherrypie();

into

async function binomial () { await cherrypie(); }

appears to make no difference whatsoever.

AndreasMadsen commented 7 years ago

@fasterthanlime Thanks, that does look suspicious. I will look at it next week after I have handed in my master thesis. In the meantime, I recommend upgrading to node v8.1.x where we landed some changes to how promises show up in async_hooks and thus also trace (https://github.com/nodejs/node/pull/13367).

fasterthanlime commented 7 years ago

Cool, thanks!

Here's the output with node v8.1.2:

=================================
 Throwing first thing
=================================
Full stack trace:
Error: throwing first thing
    at cherrypie (C:\msys64\home\amwenger\Dev\async-test\index.js:12:13)
    at binomial (C:\msys64\home\amwenger\Dev\async-test\index.js:14:40)
    at abacus (C:\msys64\home\amwenger\Dev\async-test\index.js:15:38)
    at main (C:\msys64\home\amwenger\Dev\async-test\index.js:16:22)
    at Object.<anonymous> (C:\msys64\home\amwenger\Dev\async-test\index.js:34:1)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at <anonymous>
    at checkStack (C:\msys64\home\amwenger\Dev\async-test\index.js:38:5)
    at main (C:\msys64\home\amwenger\Dev\async-test\index.js:16:11)
    at Object.<anonymous> (C:\msys64\home\amwenger\Dev\async-test\index.js:34:1)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at <anonymous>
    at checkStack (C:\msys64\home\amwenger\Dev\async-test\index.js:38:5)
    at main (C:\msys64\home\amwenger\Dev\async-test\index.js:16:11)
    at Object.<anonymous> (C:\msys64\home\amwenger\Dev\async-test\index.js:34:1)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3

=================================
 Throwing after await
=================================
Full stack trace:
Error: after timeout
    at cherrypie (C:\msys64\home\amwenger\Dev\async-test\index.js:26:13)
    at <anonymous>
    at <anonymous>
    at checkStack (C:\msys64\home\amwenger\Dev\async-test\index.js:38:5)
    at main (C:\msys64\home\amwenger\Dev\async-test\index.js:30:11)
    at <anonymous>
    at runMicrotasksCallback (internal/process/next_tick.js:86:5)
    at _combinedTickCallback (internal/process/next_tick.js:95:7)
    at process._tickCallback (internal/process/next_tick.js:161:9)
    at Function.Module.runMain (module.js:607:11)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at <anonymous>
    at checkStack (C:\msys64\home\amwenger\Dev\async-test\index.js:38:5)
    at main (C:\msys64\home\amwenger\Dev\async-test\index.js:30:11)
    at <anonymous>
    at runMicrotasksCallback (internal/process/next_tick.js:86:5)
    at _combinedTickCallback (internal/process/next_tick.js:95:7)
    at process._tickCallback (internal/process/next_tick.js:161:9)
    at Function.Module.runMain (module.js:607:11)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
AndreasMadsen commented 7 years ago

Thanks, I didn't really expect the upgrade to fix it.

It looks like there is another bug, at bootstrap_node.js:575:3 should never occur more than once per trace. I did suspect this bug existed but I could never create it. This is awesome, thanks.

fasterthanlime commented 7 years ago

Happy to help!

I have a whole suite of tests like that, because I was tired of getting useless stack traces in my error reports: https://github.com/itchio/itch/blob/cead3ba6bcbe5c46f57dc6b95b01763e73a87420/src/confidence/stacktrace.spec.ts

My current solution is using babel to transpile all Promise code to bluebird, and enable bluebird's longStackTraces collection. Which works well enough, but I feel like native v8 promises + async_hooks should be faster, since bluebird Promises are coroutine-based.

There's literally 0 time pressure on this though - before I can switch to native promises + async_hooks, electron has to release with node v8.0.0, and that'll probably take a few weeks!

AndreasMadsen commented 7 years ago

Your "Throwing first thing" creates 13 Promise instances, I'm having some trouble identifying them all. Could you demonstrate the issue where async/await is ported to the new Promise(), .then(), and .catch() API.

edit: I have pushed a new master that removes some of the at bootstrap_node.js:575:3 duplicates. Not all of them can be removed (or should be removed) as some of them are due to how node.js executes the microtask queue in combination with nextTick.

fasterthanlime commented 7 years ago

Your "Throwing first thing" creates 13 Promise instances, I'm having some trouble identifying them all. Could you demonstrate the issue where async/await is ported to the new Promise(), .then(), and .catch() API.

Interesting, the issue doesn't seem to appear with pure promises

$ npm start

> async-test@1.0.0 start C:\msys64\home\amwenger\Dev\promise-test
> node --stack_trace_limit=100 index.js

=================================
 Throwing first thing
=================================
Full stack trace:
Error: throwing first thing
    at Promise (C:\msys64\home\amwenger\Dev\promise-test\index.js:11:12)
    at Promise (<anonymous>)
    at cherrypie (C:\msys64\home\amwenger\Dev\promise-test\index.js:10:27)
    at binomial (C:\msys64\home\amwenger\Dev\promise-test\index.js:13:26)
    at abacus (C:\msys64\home\amwenger\Dev\promise-test\index.js:14:24)
    at firstThing (C:\msys64\home\amwenger\Dev\promise-test\index.js:15:21)
    at main (C:\msys64\home\amwenger\Dev\promise-test\index.js:34:3)
    at Object.<anonymous> (C:\msys64\home\amwenger\Dev\promise-test\index.js:37:1)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at Promise.catch (<anonymous>)
    at checkStack (C:\msys64\home\amwenger\Dev\promise-test\index.js:43:11)
    at firstThing (C:\msys64\home\amwenger\Dev\promise-test\index.js:15:10)
    at main (C:\msys64\home\amwenger\Dev\promise-test\index.js:34:3)
    at Object.<anonymous> (C:\msys64\home\amwenger\Dev\promise-test\index.js:37:1)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at Promise.then (<anonymous>)
    at checkStack (C:\msys64\home\amwenger\Dev\promise-test\index.js:40:18)
    at firstThing (C:\msys64\home\amwenger\Dev\promise-test\index.js:15:10)
    at main (C:\msys64\home\amwenger\Dev\promise-test\index.js:34:3)
    at Object.<anonymous> (C:\msys64\home\amwenger\Dev\promise-test\index.js:37:1)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at Promise (<anonymous>)
    at cherrypie (C:\msys64\home\amwenger\Dev\promise-test\index.js:10:27)
    at binomial (C:\msys64\home\amwenger\Dev\promise-test\index.js:13:26)
    at abacus (C:\msys64\home\amwenger\Dev\promise-test\index.js:14:24)
    at firstThing (C:\msys64\home\amwenger\Dev\promise-test\index.js:15:21)
    at main (C:\msys64\home\amwenger\Dev\promise-test\index.js:34:3)
    at Object.<anonymous> (C:\msys64\home\amwenger\Dev\promise-test\index.js:37:1)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3

=================================
 Throwing after await
=================================
Full stack trace:
Error: after timeout
    at Promise.then (C:\msys64\home\amwenger\Dev\promise-test\index.js:26:13)
    at <anonymous>
    at Promise.catch (<anonymous>)
    at checkStack (C:\msys64\home\amwenger\Dev\promise-test\index.js:43:11)
    at secondThing (C:\msys64\home\amwenger\Dev\promise-test\index.js:30:10)
    at firstThing.then (C:\msys64\home\amwenger\Dev\promise-test\index.js:34:27)
    at <anonymous>
    at runMicrotasksCallback (internal/process/next_tick.js:86:5)
    at _combinedTickCallback (internal/process/next_tick.js:95:7)
    at process._tickCallback (internal/process/next_tick.js:161:9)
    at Function.Module.runMain (module.js:607:11)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at Promise.then (<anonymous>)
    at checkStack (C:\msys64\home\amwenger\Dev\promise-test\index.js:40:18)
    at secondThing (C:\msys64\home\amwenger\Dev\promise-test\index.js:30:10)
    at firstThing.then (C:\msys64\home\amwenger\Dev\promise-test\index.js:34:27)
    at <anonymous>
    at runMicrotasksCallback (internal/process/next_tick.js:86:5)
    at _combinedTickCallback (internal/process/next_tick.js:95:7)
    at process._tickCallback (internal/process/next_tick.js:161:9)
    at Function.Module.runMain (module.js:607:11)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at Promise.then (<anonymous>)
    at cherrypie (C:\msys64\home\amwenger\Dev\promise-test\index.js:25:6)
    at binomial (C:\msys64\home\amwenger\Dev\promise-test\index.js:28:26)
    at abacus (C:\msys64\home\amwenger\Dev\promise-test\index.js:29:24)
    at secondThing (C:\msys64\home\amwenger\Dev\promise-test\index.js:30:21)
    at firstThing.then (C:\msys64\home\amwenger\Dev\promise-test\index.js:34:27)
    at <anonymous>
    at runMicrotasksCallback (internal/process/next_tick.js:86:5)
    at _combinedTickCallback (internal/process/next_tick.js:95:7)
    at process._tickCallback (internal/process/next_tick.js:161:9)
    at Function.Module.runMain (module.js:607:11)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
    at Promise (<anonymous>)
    at cherrypie (C:\msys64\home\amwenger\Dev\promise-test\index.js:24:5)
    at binomial (C:\msys64\home\amwenger\Dev\promise-test\index.js:28:26)
    at abacus (C:\msys64\home\amwenger\Dev\promise-test\index.js:29:24)
    at secondThing (C:\msys64\home\amwenger\Dev\promise-test\index.js:30:21)
    at firstThing.then (C:\msys64\home\amwenger\Dev\promise-test\index.js:34:27)
    at <anonymous>
    at runMicrotasksCallback (internal/process/next_tick.js:86:5)
    at _combinedTickCallback (internal/process/next_tick.js:95:7)
    at process._tickCallback (internal/process/next_tick.js:161:9)
    at Function.Module.runMain (module.js:607:11)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
AndreasMadsen commented 7 years ago

@fasterthanlime Well I'm no expert in async/await, but I'm pretty sure you can't just remove the async and await statements.

(async () => {})() corresponds to new Promise( () => {}) and await promise; corresponds to .then(() => promise), or something like that.

fasterthanlime commented 7 years ago

@fasterthanlime Well I'm no expert in async/await, but I'm pretty sure you can't just remove the async and await statements.

(async () => {})() corresponds to new Promise( () => {}) and await promise; corresponds to .then(() => promise), or something like that.

That's what I did though :)

 const cherrypie = () =>
    new Promise((resolve, reject) => setTimeout(resolve, 200))
    .then(() => {
      throw new Error(`after timeout`);
    })

These all behave the same:

// relay the original promise
const v1 = () => functionReturningPromise();

// wrap the original promise - if it resolves the wrapper
// will resolve, if it rejects the wrapper will reject
const v2 = () => Promise.resolve(functionReturningPromise());

// async functions "rethrow" rejections and can "return"
// resolved values asynchronously
const v3 = async () => await functionReturningPromise();

// don't write that ;)
const v4 = () => {
  return new Promise((resolve, reject) => {
    functionReturningPromise().then(resolve).catch(reject);
  });
}

edit: I should clarify - according to my understanding of async/await and promises, those should all: resolve or reject according to whatever the Promise returned by functionReturningPromise does, and should make both vx and functionReturningPromise appear in the ideal stack trace. I have no doubt that they all have subtle implementation differences though.

The noise bothers me a lot less than missing frames :)

AndreasMadsen commented 7 years ago

I have no doubt that they all have subtle implementation differences though.

They have subtle differences in the standard too. It is about how many rounds the microtask queue take. Promise.resolve(1).then((val) => Promise.resolve(val)).then(...) results in the same as Promise.resolve(1).then(...) but they behave slightly differently.

The noise bothers me a lot less than missing frames :)

I know, but that was an issue I understood :)

AndreasMadsen commented 7 years ago

Okay, I have reduced it to promises. It is not exactly the same but the issue is the same:

throwing first thing:

'use strict';

function binomial() {
  return new Promise(function binomialPromise() {
    throw new Error('throwing first thing');
  });
}

function abacus() {
  return Promise.resolve().then(function abacusThen() {
    return binomial();
  });
}

abacus().catch(function (e) {
  process._rawDebug(e);
});
Error: throwing first thing
    at binomialPromise (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:5:11)
    at binomial (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:4:10)
 ** at abacusThen (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:11:12)
    at Object.<anonymous> (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:15:15)
    at abacus (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:10:28)
    at abacus (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:10:18)
    at Object.<anonymous> (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:15:1)

after timeout:

'use strict';

function binomial() {
  return Promise.resolve(/* timeout */).then(function binomialThen() {
    throw new Error('after timeout');
  });
}

function abacus() {
  return Promise.resolve().then(function abacusThen() {
    return binomial();
  });
}

abacus().catch(function (e) {
  process._rawDebug(e);
});
Error: after timeout
    at binomialThen (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:5:11)
    at Object.<anonymous> (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:15:15)
    at abacus (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:10:28)
    at abacus (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:10:18)
    at Object.<anonymous> (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:15:1)
AndreasMadsen commented 7 years ago

I have debugged it some more. The stack trace is actually correct, the problem is that v8 calls Error.prepareStackTrace when .stack is called and not when new Error() is called.

I will think about possible solutions to this, but I'm not sure it can be fixed.

throwing first thing


async function binomial() {
  const a = new Error('throwing first thing'); a.stack; throw a;
}

async function abacus() {
  await binomial();
}

async function main() {
  try {
    await abacus();
  } catch (e) {
    process._rawDebug(e.stack);
  }
}

main();
Error: throwing first thing
    at binomial (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:3:13)
    at abacus (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:7:9)
    at main (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:12:11)
    at Object.<anonymous> (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-first.js:18:1)

after timeout


async function binomial() {
  await Promise.resolve(/* timeout */);
  const a = new Error('after timeout'); a.stack; throw a;
}

async function abacus() {
  await binomial();
}

async function main() {
  try {
    await abacus();
  } catch (e) {
    process._rawDebug(e.stack);
  }
}

main();
Error: throwing first thing
    at binomial (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:4:13)
    at binomial (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:3:3)
    at binomial (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:3:3)
    at abacus (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:8:9)
    at main (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:13:11)
    at Object.<anonymous> (/Users/Andreas/Sites/node_modules/trace/test/scripts/await-throwing-second.js:19:1)
fasterthanlime commented 7 years ago

Ah, so the only way out would be to have a new hook in node when it creates the Exception (rather than when .stack is accessed for the first time)?

AndreasMadsen commented 7 years ago

Ah, so the only way out would be to have a new hook in node when it creates the Exception (rather than when .stack is accessed for the first time)?

Yep. I tried overwriting global.Error and Error.captureStackTrace non of those allowed me to get notified, so an extra hook is needed. Allowing Error.captureStackTrace to be overwritten or extended, seems like the most straight-forward approach.

The primary reason for lazy creation of .stack is the string generation takes time. I think a good solution is to continue to delay the .stack formatting, but allow the callSite array to be modified upon new Error creation.

fasterthanlime commented 7 years ago

I've tried following the discussion in nodejs/node but it flew way over my head :)

Is there any workaround that would work with node v8.2.1? Or is it too early still?

No pressure at all btw, just checking in as I'm still very interested in this.

AndreasMadsen commented 7 years ago

@fasterthanlime I'm not sure what discussion that is. There is a somewhat interesting discussion here: https://github.com/nodejs/node/issues/11865

Nothing sufficiently new has happened in v8.2.1. I suppose it might be possible to setup node errors and users error to not lazy-build the stack, but even so, native JavaScript are still going to lazy-build the stack.

I think the only way to really solve this, is to involve the v8 team. I asked in https://github.com/nodejs/node/issues/11865 if we can get a new Error notification feature.

jbunton-atlassian commented 6 years ago

I think I have a solution for this in my follow-promise-resolve branch. I use the promiseResolve async hook callback to link to extra stack frames. I also waiting until the stack is being printed to join frames rather than doing so in asyncInit, this captures more info.

It passes the existing tests as well as my new ones, however it needs a little more cleanup before I raise a PR.

AndreasMadsen commented 6 years ago

@jbunton-atlassian I'm excited that you are investigating this, but I'm very skeptical.

I'm very skeptical because no matter what you won't get the frames from the point of view where new Error() was created, unless you capture new Error(). The issue is actually bigger than just promises.

function asyncFunction(callback) {
  process.nextTick(callback, new Error('error'))
}

asyncFunction(function (err) {
  process.nextTick(() => throw err)
})

will suffer from the same issue, because the long-stack-trace is collected at throw err not new Error().

I use the promiseResolve async hook callback to link to extra stack frames.

Using the promiseResolve "solves" a different issue, where the stack trace for what is between the start of the promise and the resolve call isn't included.

I also waiting until the stack is being printed to join frames rather than doing so in asyncInit, this captures more info.

As I see it, you just represent the long-stack-trace as a linked list. So I don't really see what extra information you get. Can you clarify?

It passes the existing tests as well as my new ones, however it needs a little more cleanup before I raise a PR.

Okay, I will be happy to review when you are done.

jbunton-atlassian commented 6 years ago

Hi there. I think I've solved this in #40. I'd love any feedback or testing anybody could give this code :)

You can try it out by installing it from my repo:

npm install 'git://github.com/jbunton-atlassian/trace#a4e78d89e09ab4830f302bf85a30a528a5746e0b'