Summit Topic: Promises

[BridgeAR]

Abstract

Last summit the promise debugging group was very valuable and it's time to recap and continue the ongoing efforts.
To do so here's a rough agenda for the meeting. Please feel encouraged to suggest further topics.

Proposed agenda

• Current status / what has happened since out last meeting?
• New promise events to debug code (multiple resolves)
• Discuss the proposed default behavior for unhandled rejections in Node core (Refs: src: exit on gc unhandled rejection nodejs/node#20097)
• The Netflix survey and it's conclusions
• Zero cost async stack traces with async / await (thanks a million @bmeurer)
• New promise APIs in core (DNS, streams async iterators, ...)
• Next steps

@nodejs/promises-debugging for visibility.

[misterdjules]

@BridgeAR That looks great!

I was wondering whether:

New promise APIs in core (DNS, streams async iterators, ...)

would be better for the more general "Promises" session, as it seems it's not specific to debugging.

[BridgeAR]

@misterdjules I fixed the title as this should actually just be the agenda for the general promises part.

[BridgeAR]

One more point that we should talk about:

util.promisify likely becomes an anti-pattern soon due to loosing the stack trace compared to async / await.

Some raw takes for me on this:

• we should make sure that Node internal code always uses async / await and not regular promises.
• we should discourage usage of that function and recommend to use async / await everywhere throughout the ecosystem, if possible.

[bmeurer]

You'll loose the stack trace with any callback based API. I was already thinking that we could introduce some kind of zone mechanism in Node to provide V8 with context information necessary to rebuild the stack trace.

[benjamingr]

util.promisify likely becomes an anti-pattern soon due to loosing the stack trace compared to async / await.

Can you explain this to me? Isn't the stack trace lost only after the promisifed functions?

I think this is more of a promises-guide concern (tell people to always promisify at the lowest level)

[benjamingr]

Would also love it if the sinon issue was discussed (testing fake timers with async functions)

[devsnek]

will remote participation be available?

[mcollina]

Likely similar to the modules session. Il giorno sab 13 ott 2018 alle ore 07:14 Gus Caplan < notifications@github.com> ha scritto:

…

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[BridgeAR]

To join the meeting please use zoom: https://zoom.us/j/327915725
Update: Having problem with the microphone. I am trying to fix it quickly but I can not give any guarantees.

[BridgeAR]

Here we go https://zoom.us/j/756090104

[mmarchini]

Link for minutes: https://docs.google.com/document/d/11Wk39aseOsMEq0T9Hz9wDadSxZucIzSgqWo7QgpIWjc/edit?usp=sharing