Issue #7791 has been updated by trans (Thomas Sawyer).


@resenfeld After the exception is raised, you can still create symbols. The point is, now you know somethings up and you need to deal with it. So once raised the idea is that you'd report the error (log and redirect user) and then shut down the process, effectively clearing the memory.

Admittedly I am thinking more in terms of short-running processes. If you are using a long-running process to serve many user requests then maybe that's a not as ideal here. But the basic idea remains. Handle the error and shut down. Your server should spin up a new process to take its place on demand. Added bonus, you can log the request IP, maybe if it happens a few times from the same address, you block it.

----------------------------------------
Feature #7791: Let symbols be garbage collected
https://bugs.ruby-lang.org/issues/7791#change-35933

Author: rosenfeld (Rodrigo Rosenfeld Rosas)
Status: Feedback
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: next minor


Lots of Denial-of-Service security vulnerabilities exploited in Ruby programs rely on symbols not being collected by garbage collector.

Ideally I'd prefer symbols and strings to behave exactly the same being just alternate ways of writing strings but I'll let this to another ticket.

This one simply asks for symbols to be allowed to be garbage collected when low on memory. Maybe one could set up some up-limit memory constraints dedicated to storing symbols. That way, the most accessed symbols would remain in that memory region and the least used ones would be reclaimed when the memory for symbols is over and a new symbol is created.

Or you could just allow symbols to be garbage collected any time. Any reasons why this would be a bad idea? Any performance benchmark demonstrating how using symbols instead of strings would make a real-world software perform much better?

Currently I only see symbols slowing down processing because people don't want to worry about it and will often use something like ActiveSupport Hash#with_indifferent_access or some other method to convert a string to symbol or vice versa...


-- 
http://bugs.ruby-lang.org/