On 3 July 2015 at 06:25, Neil Girdhar <mistersheik@gmail.com> wrote:
Why would it require "a lot of extra memory"? A program text size is measured in megabytes, and the AST is typically more compact than the code as text. A few megabytes is nothing.
It's more complicated than that. What happens when we multiply that "nothing" by 10,000 concurrent processes across multiple servers. Is it still nothing? How about 10,000,000? What does keeping the extra data around do to our CPU level cache efficiency? Is there a key data structure we're adding a new pointer to? What does *that* do to our performance? Where are the AST objects being kept? Do they become part of the serialised form of the affected object? If yes, what does that do to the wire protocol overhead for inter-process communication, or to the size of cached bytecode files? If no, does that mean these objects may be missing the AST data when deserialised? When we're talking about sufficiently central data structures, a few *bytes* can end up counting as "a lot". Code and function objects aren't quite *that* central (unlike, say, tuple instances), but adding things to them can still have a significant impact (hence the ability to avoid creating docstrings). Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia