Have Sentry detect when a promise never resolves

[AbhiPrasad]

Problem Statement

Have sentry detect when a promise never resolves and give the stacktrace to where the promise was created.

Can maybe be done with async context, and can use v8 inspector API to get stacktrace.

Solution Brainstorm

Something like https://github.com/gajus/timeout-idle-promise?

We'd need to find a way to filter out intentionally unresolved promises (we use this technique for the ANR watchdog child process).

Maybe we can also look at open handles?

[timfish]

Here's some prior art using async_hooks:
https://gist.github.com/Swizec/30df527907e3488a546075b3ec691dd9

But it says:

Unfortunately it can't get a reference to execution context, which diminishes its usefulness

Maybe if the debugger is attached and you call debugger; you'll get more context?

[AbhiPrasad]

I'm worried about the event loop pressure from several setTimeout calls, perhaps we also need a watchdog that just iterates through a set of watched asyncIds and updates them every X seconds.

[timfish]

I'm worried about the event loop pressure from several setTimeout calls

You could just store the ids and check periodically which have been seen at multiple intervals.

It's worth noting that you can't console log in any of the hooks because that itself creates contexts and you get a stack overflow. This means everything in the hooks also needs to be sync too and not create promises unless you're willing to filter them to prevent the circular calls. ie. it would be very easy with this to break stuff!

You can however get a new Error().stack in the init callback and see where the promise was created:

Error
  at AsyncHook.init (/Users/tim/Documents/Repositories/promise-testing/test.js:17:7)
  at emitInitNative (node:internal/async_hooks:202:43)
  at emitInitScript (node:internal/async_hooks:505:3)
  at promiseInitHook (node:internal/async_hooks:324:3)
  at promiseInitHookWithDestroyTracking (node:internal/async_hooks:328:3)
  at new Promise (<anonymous>)
  at Object.<anonymous> (/Users/tim/Documents/Repositories/promise-testing/test.js:67:17)
  at Module._compile (node:internal/modules/cjs/loader:1119:14)
  at Module._extensions..js (node:internal/modules/cjs/loader:1173:10)
  at Module.load (node:internal/modules/cjs/loader:997:32)