JRuby too slow for development

September 27, 2011

A controversial title which I hope I will be able to amend.

I'm new to JRuby, and the following may be due to my ignorance, which I am trying to address.

Two identical rails projects with almost identical Gemfile's. One running under JRuby 1.6.3 and the other on MRI 1.8.7p352. Running exactly the same specs. JRuby is 20x slower!!!

JRuby

➥  time rspec spec

Person
  can have pets (FAILED - 1)

Pet
  add some examples to (or delete) /Users/andy/repos/diabolo/jruby/rails-example/spec/models/pet_spec.rb (PENDING: Not Yet Implemented)

Pending:
  Pet add some examples to (or delete) /Users/andy/repos/diabolo/jruby/rails-example/spec/models/pet_spec.rb
    # Not Yet Implemented
    # ./spec/models/pet_spec.rb:4

Failures:

  1) Person can have pets
     Failure/Error: alice.pets << fluffy
     NoMethodError:
       undefined method `pets' for #<Person:0x7ec89b0a>
     # org/jruby/RubyKernel.java:238:in `method_missing'
     # ./spec/models/person_spec.rb:7:in `(root)'
     # org/jruby/RubyKernel.java:2061:in `instance_eval'
     # org/jruby/RubyArray.java:2336:in `collect'
     # org/jruby/RubyArray.java:2336:in `collect'

Finished in 0.248 seconds
2 examples, 1 failure, 1 pending

Failed examples:

rspec ./spec/models/person_spec.rb:4 # Person can have pets
org.jruby.exceptions.RaiseException: (SystemExit) exit

real    0m21.324s
user    0m0.001s
sys 0m0.004s

MRI

➥  time rspec spec

Person
  can have pets (FAILED - 1)

Pet
  add some examples to (or delete) /Users/andy/repos/diabolo/mri/rails-example/spec/models/pet_spec.rb (PENDING: Not Yet Implemented)

Pending:
  Pet add some examples to (or delete) /Users/andy/repos/diabolo/mri/rails-example/spec/models/pet_spec.rb
    # Not Yet Implemented
    # ./spec/models/pet_spec.rb:4

Failures:

  1) Person can have pets
     Failure/Error: alice = Person.create!
     ActiveRecord::StatementInvalid:
       Could not find table 'people'
     # ./spec/models/person_spec.rb:5

Finished in 0.01325 seconds
2 examples, 1 failure, 1 pending

Failed examples:

rspec ./spec/models/person_spec.rb:4 # Person can have pets

real    0m1.981s
user    0m1.433s sys    0m0.546s