From: "Iñaki Baz Castillo" <ibc@...>
Date: 2009-03-30T17:09:29+09:00
Subject: Symbols garbage collector in Ruby1.9, fixed?

Hi, in Ruby 1.8 there is an issue when adding more and more Symbols
since they remain in memory and are never removed.

I'm doing a server in Ruby that receives messages with headers (From,
To, Subject, X-Custom-Header-1...) and after parsing I store the
headers in a hash using symbols as keys:

  headers = {
    :from => "alice@aaa.com",
    :to => "bob@bbb.com",
    :"x-custom-header-1" => "Hi there"
  }

I could use strings as keys instead of symbols, but I've checked that
getting a Hash entry is ~25% faster using Symbols.

The problem is that I could receive custom headers so for each one a
new Symbol would be created. An attacker could send lots of custom
headers to fill the server memory and cause a denial of service.

Perhaps this is solved in Ruby 1.9? any suggestion on it? Thanks a lot.


-- 
Iñaki Baz Castillo
<ibc@aliax.net>