react-native: [Bundle] "Allocation failed - process out of memory" in OSX making bundle

Okay, this is a dirty dirty hack, but after staring at the internals of the packager for several hours (and not understanding it) I’ve found a way to get the packager to complete a bundle.

edit node_modules/babel-traverse/lib/index.js and add this to the top of the file:

function scheduleGc() {
  if (!global.gc) {
    console.log('Garbage collection is not exposed');
    return;
  }
var timeoutId = setTimeout(function(){
    global.gc();
    console.log('Manual gc', process.memoryUsage());
    scheduleGc();
  },30000);
timeoutId.unref();
}
// call this in the startup script of your app (once per process)
scheduleGc();

Now you need to call the bundler like this (to enable garbage collection):

node --expose-gc --max_old_space_size=4096 "./node_modules/react-native/local-cli/cli.js" bundle --entry-file ./index.ios.js --platform ios --dev false --reset-cache true --bundle-output "MyApp.app/main.jsbundle" --assets-dest "MyApp.app"

NOTE: I’m not sure what the values are supposed to be for --bundle-output and -assets-dest`, but the key thing to note is the –expose-gc flag which allows this to work.

So, what is this doing? For me at least, the bundler was running out of memory during babel transformation (or ast building?). Putting that code at the top of that file runs garbage collection every 30 seconds (might have to tune it depending on your machine). It seems to work well enough to stop V8 from running out of heap memory. But yes, it’s a dirty dirty hack.

In general, how do we fix this? Adding a fix value in the code seems not good. But calculating a possible value for memory size could be reasonable? Sth like:

if ram <= 4GB, use 2,5GB if ram <= 8GB, use 4GB else use 8GB

Another way could be to read if there is an environment var set and use it (which would be my favourite).

@Takeno Thanks for digging into this issue! Maybe you’d be interested to submit a PR to add a memory limit option, or at least to document the issue in the Troubleshooting section?

Hey Takeno, thanks for reporting this issue!

React Native, as you’ve probably heard, is getting really popular and truth is we’re getting a bit overwhelmed by the activity surrounding it. There are just too many issues for us to manage properly.

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