"ng build --prod" can consume all available RAM

[Chris Sharp]

Found when installing stock-ish master servers for feedback fest. When running the "ng build --prod" step on a server with 4GB RAM/1 GB swap, the process is halted with the easy-to-miss message "Killed":

39% building 245/247 modules 2 active ...eg2/node_modules/@angular-devkit/build-optimizer/src/build-optimizer/webpack-loader.js??ref--18-0!/home/opensrf/Evergreen/Open-ILS/src/eg2/node_modules/@ngtools/webpack/src/index.js!/home/opensrf/Evergreen/Open-ILS/src/eg2/src/app/staff/share/holds/grid.component.ngfactory.jsKilled

Increasing swap to 4GB on each server resolved the immediate issue, but further research shows that this is not an unheard-of issue in NodeJS/Angular projects:

https://github.com/angular/angular-cli/issues/1652

Apparently, garbage collection can be explicitly controlled with the "max-old-space-size" parameter.

https://stackoverflow.com/questions/48387040/nodejs-recommended-max-old-space-size

It would be nice to see confirmation of the issue before making any drastic changes, but perhaps we can document the problem and/or hard-code a sane default somewhere?

Output of "ng --version":

Angular CLI: 8.3.12
Node: 12.13.0
OS: linux x64
Angular: 8.2.11
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router

Package Version
-----------------------------------------------------------
@angular-devkit/architect 0.803.12
@angular-devkit/build-angular 0.803.12
@angular-devkit/build-optimizer 0.803.12
@angular-devkit/build-webpack 0.803.12
@angular-devkit/core 8.3.12
@angular-devkit/schematics 8.3.12
@angular/cli 8.3.12
@angular/http 7.2.15
@ngtools/webpack 8.3.12
@nguniversal/express-engine 8.1.1
@schematics/angular 8.3.12
@schematics/update 0.803.12
rxjs 6.5.3
typescript 3.5.3
webpack 4.39.2

[Jane Sandberg (sandbergja)]

I'm curious if the new option to use esbuild rather than webpack in Angular 14 might help (https://blog.angular.io/angular-v14-is-now-available-391a6db736af), once we do that upgrade (bug 1982376)

[Jane Sandberg (sandbergja)]

Thanks for this report and research, Chris! I've seen the same in VMs that don't have a lot of memory, and can confirm that explicitly setting max-old-space-size can get things working again.

Figuring out a sensible default seems difficult, so I've opted for the docs approach.

Branch here: user/sandbergja/lp1863921_ng_build_prod -- I also took the opportunity to update our install docs from `ng build --prod` to `ng build --configuration="production"` to avoid a deprecation warning.

[Andrea Neiman (aneiman)]

Pushed to master through rel_3_9. Thanks Jane & Chris!