"Every request spawns a fresh process. Deploying a new version is replacing one file. That means no server restart and no downtime. New requests simply pick up the new binary."

I think that's why FastCGI exists. It is the equivalent of PHP's "Swoole" or "FrankenPHP" or "amphp" or Laravel's "octane", etc. Each process is long-lived and tries to clean up its state as much as possible between requests. Forking a new process can take around 8ms (https://news.ycombinator.com/item?id=19005586)

When I was building https://github.com/Qbix/webserver in PHP, I was faced with forking a new process per request. I implemented fork-per-request at first, similar to PHP-FPM and then implemented the "FastCGI" approach of long-lived processes that clean up after each request. (Modern PHP has introspection so the engine can know what to clean up, before calling the php files to handle things.) However, some things are not really possible to completely reset in PHP, and you have to be careful with database connection pools, etc. Typically those are left open even by preforking processes like php-fpm.

Anyway, I ended up flipping it: use the "FastCGI" approach as a default, and if the original PHP code doesn't work (rare), then for that app, you can choose the regular CGI approach of forking a process per request. That way you get maximum speed by default, and manually opt into safety (this is an exception to my usual priorities).

PHP is actually quite fast. But I was also interested in transpiling it to C. So I built the transpiler at: https://ulanguage.org/playground ... used Claude to transform about 1000 PHP functions to their native equivalents, but if you use any of the others, it would hook into the Zend runtime and link with it. (There are some nuances with zvals and objects, and resources in previous PHP versions, but I managed to overcome them.) By the way, it also works with Node and Python FFI the same way.

You can basically now take PHP, Python or Javascript/Typescript code, and speed up the CPU-bound parts about 10-50x. A lot of that is because of string and JSON handling. Many web apps use strings and JSON a lot. So underneath, I had the compiler use "ropes" for the strings, and avoid concatenation. It also parallelizes the JSON encode and decode into code that can run on multiple cores at once, i.e. large JSON payloads are encoded and decoded in parallel. Those are just huge speedups.

Anyway... all of this is mostly focused on speed optimization, so you can solve the literally C100K problem (forget C10K) today, on a regular box. If you don't need speed or FastCGI, your approach is fast enough for the vast majority of applications.

PS: By the way, if you fork after your program already loaded the framework and initialized the configuration, then you can run a lot more workers, literally 10x-100x more of them, because Linux and Mac will share all the loaded memory between processes, and do Copy-On-Write only on dirty pages. And when your request is done, and the process exits, that custom memory is efficiently cleaned up by the OS. It is this feature that allowed me to finally get the best of both worlds... run all existing PHP code, that makes blocking I/O requests all over the place to the database, filesystem, network etc. while at the same time being able to handle 100,000 requests in flight at the same time! Swoole and FrankenPHP can't do that.