Someone posted something similar here, however I'm curious to which would run faster and save me more memory? I know that Matz as made many enhancements in 1.9 but I also stand behind the decisions the Phusion guys have made as well.
My question is which is the best to run on my VM which only has 265mb of ram?
Since Rails 3 will be highly optimized for Ruby 1.9, and Ruby 1.9 has MANY similar optimizations that REE has, Ruby 1.9 will likely be very close in memory usage, and faster than REE.
Yehuda talk about Rails 3:
http://railsonedge.blogspot.com/2009/03/yehuda-katz-talks-about-rails-30.html
http://www.oreillynet.com/pub/e/1338
Tiny Google Group discussion about REE for Ruby 1.9
http://groups.google.com/group/emm-ruby/browse_thread/thread/b5ab0f02c3faac7e#
The 1.8.7 EE would be a safer bet right now. The main problem with Ruby apps is the distinct inability to share memory (the copy-on-write issue) and fixing that is the main aim of EE.
I manage 8 different sites, all running versions of our product running on a mix of Rails, Merb, Rack and Thin on all running on plain old Ruby 1.8.7. For a small Rails application, 256Mb would be ok.
You can see from below that our application is comprised of 6 processes; Rails (2) and Merb (4). The Rails processes (mongrel_rails) are using 104Mb of actual memory each. Our app is reasonably complex with responses of the order of 0.5s so we are looking at being able to handle around 4/5 concurrent users from the 2 Rails processes. Take a look at the shockingly small amount of shared memory to see why EE makes so much sense. I'd expect a much higher shared section with EE.
As they say 'your experience may differ' but there's nothing stopping you from even trying plain old Ruby/Rails and only moving to EE if you need to.
top - 08:57:48 up 128 days, 11:57, 1 user, load average: 0.07, 0.09, 0.09
Tasks: 76 total, 1 running, 75 sleeping, 0 stopped, 0 zombie
Cpu(s): 2.4%us, 0.1%sy, 0.0%ni, 96.2%id, 0.0%wa, 0.0%hi, 0.0%si, 1.3%st
Mem: 1048796k total, 745840k used, 302956k free, 5192k buffers
Swap: 2097144k total, 634636k used, 1462508k free, 124816k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
25875 root 20 0 271m 104m 4616 S 0 10.2 141:07.07 mongrel_rails
25872 root 20 0 263m 102m 4648 S 0 10.0 142:11.86 mongrel_rails
21089 root 20 0 192m 84m 2436 S 0 8.3 2:52.03 merb
21088 root 20 0 173m 80m 2436 S 0 7.9 2:51.73 merb
21090 root 20 0 179m 74m 2436 S 0 7.3 2:42.83 merb
21086 root 20 0 113m 34m 1660 S 11 3.4 3752:37 merb
4874 clavis 20 0 122m 31m 3804 S 0 3.1 127:52.87 profile_report
3662 mysql 20 0 368m 22m 3280 S 0 2.2 464:01.81 mysqld