PHP: Reduce memory requirements – lower the HEAP size from 1GB

[adamziel]

Warning

This is more important since Loopback Request Support landed as we're now creating more PHP instances.

PHP is currently compiled to allocate 1024M of memory when it boots, and it limits the number of Playgrounds you can run concurrently especially on low-resource devices:

wordpress-playground/packages/php-wasm/compile/php/Dockerfile

Line 870 in 6668457

-s INITIAL_MEMORY=1024MB \

Let's see how low can we go while still keeping 256M available for running requests.

Importantly, MEMFS files are also kept at heap. I wonder what else is.

Resources

Discussions related to measuring memory usage

• https://github.com/WordPress/wordpress-playground/wiki/Performance-testing-resources
• Run on Cloudflare Workers #69

Related to

• PHP memory leak #1128
• Web PHP: Increase memory limit to 256 M #1232

@brandonpayton @ellatrix