How to work with a large file and limited RAM?

Question

PHP

Let's say there is data that needs to be processed and made up of a large xml, let's say 150-200MB, and the RAM on the machine is only 2GB, which are clogged by 80-90% when the script is running.
What should be the algorithm of the program so as not to keep the entire file in memory, but also to work with the file normally through simple_xml lib?

Answer 1

read about xml_parse and SAX model

Answer 2

Do not work with the file "via simple_xml lib", which is not intended for large files in principle, which is even mentioned on PHP.net
There you can easily find alternative libraries for working with XML that do not try to load it entirely into memory.