It seems the memory problem comes from the SourceMapGenerator.toJSON function https://gist.github.com/gphilipp/10cebb3aba7afbafbc1cca7b265a7b7e#file-short_build_rn_memory-log-L108-L109. the log includes gc traces.

I can’t find any settings which can effectively increase the maximum memory allocated to the node process, and I’ve tried them all, with various versions of node

The good news it that there might be some hope, as we have the exact same issue than someone who filed it against https://github.com/facebookincubator/create-react-app. Watch this issue: https://github.com/facebookincubator/create-react-app/issues/2555

And someone uploaded yesterday a project to reproduce it reliably, so the issue will most likely be fixed in the near future: https://github.com/facebookincubator/create-react-app/issues/2555#issuecomment-313774797

Note that the memory issue occurs with RN 0.45.1 not with 0.44.2, I haven’t tried 0.46 yet (but it seems to break re-natal right ?).