Exceeded the maximum call stack inside an async function leads to an uncaught promise, even if await is used properly

[wryun]

Running:

async function x() { 
 await x(); 
} 
(async function () { 
 try { 
 await x(); 
 } catch (e) { 
 console.log(e); 
 } 
})() 

Leads to an uncaught promise:

; node t.js
(node:434) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): RangeError: Maximum call stack size exceeded

Running the same thing with babel transpiling to bluebird coroutines works fine. I guess there are two questions?

• is this a bug?
• if it is a bug, should I be filing it against node or v8?

[bnoordhuis]

The RangeError should bubble up to the try/catch block so yes, I would say this is a (V8) bug.

It may have been fixed upstream in V8 already but I can't test that right now and a quick code search didn't turn up anything.

[vsemozhetbyt]

In the Node.js canary with V8 6.2.172, this code still produces the same unhandled promise rejection.

[vsemozhetbyt]

Strangely, in the Google Chrome canary with the same V8 6.2.172, it seems to bubble:

RangeError: Maximum call stack size exceeded
 at x (<anonymous>:1:1)
 at x (<anonymous>:2:11)
 at x (<anonymous>:2:11)
 at x (<anonymous>:2:11)
 at x (<anonymous>:2:11)
 at x (<anonymous>:2:11)
 at x (<anonymous>:2:11)
 at x (<anonymous>:2:11)
 at x (<anonymous>:2:11)
 at x (<anonymous>:2:11)

[wryun]

Sounds like I should file against Node, referencing this? (thanks @vsemozhetbyt for actually doing the investigation of Chrome behaviour against the right V8)

[bnoordhuis]

I checked with V8 ToT today (nominally 6.2.218) and it works there:

$ ./out.gn/x64.release/d8 tmp/bug778.js 
RangeError: Maximum call stack size exceeded

(Yes, no stack trace - you get one if you console.log(e.stack) instead.)

I figured out what the problem is and it's a known issue: console.log() is instantiated lazily and that fails under stack overflow conditions. That is, adding a no-op console.log makes the test work:

console.log; // Force instantiation.
async function x() { 
 await x(); 
} 
(async function () { 
 try { 
 await x(); 
 } catch (e) { 
 console.log(e); 
 } 
})() 

And that prints:

$ ./out/Release/node ../v8/tmp/bug778.js 
RangeError: Maximum call stack size exceeded
 at x (/home/bnoordhuis/src/v8/tmp/bug778.js:1:1)
 at x (/home/bnoordhuis/src/v8/tmp/bug778.js:3:11)
 # etc.

cc @addaleax - since this keeps coming up, how about we simply instantiate log(), error(), etc. eagerly in bootstrap_node.js?

[addaleax]

cc @addaleax - since this keeps coming up, how about we simply instantiate log(), error(), etc. eagerly in bootstrap_node.js?

Yeah, sounds okay. ;)

[bnoordhuis]

nodejs/node#14791

[gireeshpunathil]

looks like the underlying issue is resolved, close-able?
/cc @bnoordhuis

[bnoordhuis]

Node.js tries to work around it on a best-effort basis. I'll close this out.