> I think the killer feature of PHP is its shared-nothing architecture, tear-down at every request (or every x requests if you're using php-fpm) which has proved remarkably successful as it is so resilient.
I agree. Shared nothing is definitely the killer feature.
Even if php-fpm is tear down at every x requests, each request still starts afresh in which each needed PHP file is required and loaded again. This is not slow because of opcode caching means that parsing etc. does not need to be done afresh. PHP just pulls from the opcode cache. At the end of the request the request is torn down. The interpreter instance might be reused again for performance (though that may be torn down every x request also as you implied with php-fpm for instance).
When you want to find out why something did not work in PHP you just need to go back to the start of the request and work your way from here. With a stateful system like Django (Python) or nodejs (JavaScript) you need to worry about the state of the full server in addition to what happen in a specific request.
This is an ideal model of course because large PHP implementations uses caching (in things like redis) to speed things up and the cached state could be the one introducing a bug. However, in practice, PHP tries to put in most of the state in a relational db so debugging a PHP script is much simpler due to this shared nothing feature.
I agree. Shared nothing is definitely the killer feature.
Even if php-fpm is tear down at every x requests, each request still starts afresh in which each needed PHP file is required and loaded again. This is not slow because of opcode caching means that parsing etc. does not need to be done afresh. PHP just pulls from the opcode cache. At the end of the request the request is torn down. The interpreter instance might be reused again for performance (though that may be torn down every x request also as you implied with php-fpm for instance).
When you want to find out why something did not work in PHP you just need to go back to the start of the request and work your way from here. With a stateful system like Django (Python) or nodejs (JavaScript) you need to worry about the state of the full server in addition to what happen in a specific request.
This is an ideal model of course because large PHP implementations uses caching (in things like redis) to speed things up and the cached state could be the one introducing a bug. However, in practice, PHP tries to put in most of the state in a relational db so debugging a PHP script is much simpler due to this shared nothing feature.