Continuous crashes on React Native Android

[alexanderson1993]

Continuous crashes on React Native Android

[nevir]

Alright! @alexanderson1993, the fix for your situation is to add the following to index.js:

import 'core-js/es6/symbol';
import 'core-js/es6/set';
import 'core-js/es6/map';

The root cause here is that RN fails to correctly polyfill Symbol in the Android environment (the issue linked above). So, we explicitly load that polyfill, and also Set/Map for good measure, as Hermes also relies on those.

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I'm going to see if I can have Hermes detect this case and throw a helpful error…

[nevir]

Aha, nope, it's a RN packager issue: facebook/react-native#4676

[nevir]

I'm sorry for the delay on this issue. Working on getting my machine set up for android again (I've gone and goofed my SDK/NDK somewhere)

In the meantime, do you have a stack trace handy—or remember what error was being thrown?

[alexanderson1993]

I'm afraid I'm not technically savvy enough to be able to pull up a stack trace or even the error thrown. The app crashed immediately after the request was made, and I was only able to track down apollo-cache-hermes as the culprit after a lot of trial and error.

[nevir]

Alright, I'm able to reproduce this one! Not sure exactly what's going on, yet. Here's what I know so far:

• The app is running out of memory and being killed by the OS
• It occurs before apollo client even initiates the network request (the configured apollo link is not called)
• None of Hermes' verbose logging triggers before the OOM occurs

[nevir]

Actually, interestingly, the OOM occurs sometime before Hermes' query interface is called.

I have a hunch that it's similar to zloirock/core-js#368, but can't prove that yet

[nevir]

Aha! Nope, it is getting into Hermes' read call, somewhat. I've narrowed it down to this loop:

apollo-cache-hermes/src/context/QueryInfo.ts

Line 85 in 61b59ad

for (const name of this.variables) {

It iterates forever for your query (when consuming an empty set), emitting undefined until OOM. Might be a tslib bug, or we might be passing unexpected data to it

[nevir]

Oof, it may be a tslib bug. Just filed microsoft/tslib#59 to get some more eyes on it. Might also be that react-native android is incorrectly polyfilling Set/Map...

[alexanderson1993]

This is fabulous! Many thanks!

[nevir]

Hopefully this error helps people from having to go down this rabbit hole again:

[zasyadev]

Alright! @alexanderson1993, the fix for your situation is to add the following to index.js:

import 'core-js/es6/symbol';
import 'core-js/es6/set';
import 'core-js/es6/map';

The root cause here is that RN fails to correctly polyfill Symbol in the Android environment (the issue linked above). So, we explicitly load that polyfill, and also Set/Map for good measure, as Hermes also relies on those.

I'm going to see if I can have Hermes detect this case and throw a helpful error…

Thanks @nevir it worked like a charm