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


@rosenfeld I get your points. My solutions certainly is not perfect and has tough issues to deal with, certainly. But what alternative do you have really? You are under DoS attack, your whole server is about to go down! Better to restart the server, automate the blocking of the offending IP and carry on. The alternative right now is just crash and burn.

Also, how much is GCing symbols going to help anyway? DoS attacks usually involve multiple requests. If they start feeding your app symbols ad nauseum, then you server is just going spend most of its time throwing away symbols. It might not complete crash but it will run like mud.

But I am no expert in any of this. Which is why I originally posited it as a question.
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Feature #7791: Let symbols be garbage collected
https://bugs.ruby-lang.org/issues/7791#change-35938

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...


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