Hopefully I'm doing something stupid here. I was trying to use pessimistic locking on a rails 2.3.4 project and it just doesn't seem to work. The issue was showing up on both OSX and Linux.
I've created a simplified reproducible for 2.3.10 for discussion
purposes. I'll publish the full transcript of the steps I took to
create the project later, but for now, I've got a single model Foo with
a single Bar value that's a string. I create a single Foo and saved it.
In one console window I run:
Foo.transaction do
f = Foo.find(1, :lock => true)
1.upto(10000000) { |i| puts i }
end
I was under the assumption I wouldn't be able to access that row at all
until I finished printing out 10 million numbers. But while that is
running, I can go to another console window and get to it:
johnmudhead:locktest grant$ script/console
Loading development environment (Rails 2.3.10)
>> f = Foo.find(1)
=> #<Foo id: 1, bar: "AAAAAAAAAAAAAAA!", created_at: "2010-11-01
19:50:58", updated_at: "2010-11-01 19:50:58">
That seems like I'm reading the row when I should be locked out of it.
I have confirmed that I'm using the InnoDB backend on MySQL, which
supports row level locking.
Anyone have any advice or tips? Do I have a gross misunderstanding of
pessimistic locks in ruby.
A full log of my reproducible case follows...
Thanks,
--
Grant
"I am gravely disappointed. Again you have made me unleash my dogs of war."
johnmudhead:~ grant$ cd src
johnmudhead:src grant$ rails _2.3.10_ locktest
create
create app/controllers
create app/helpers
...
create log/development.log
create log/test.log
johnmudhead:src grant$ cd locktest/
johnmudhead:locktest grant$ script/generate model foo bar:string
exists app/models/
exists test/unit/
exists test/fixtures/
create app/models/foo.rb
create test/unit/foo_test.rb
create test/fixtures/foos.yml
create db/migrate
create db/migrate/20101101194756_create_foos.rb
johnmudhead:locktest grant$ cat config/database.yml
# SQLite version 3.x
# gem install sqlite3-ruby (not necessary on OS X Leopard)
development:
adapter: mysql
database: locktest
host: localhost
encoding: utf8
user: root
pool: 5
timeout: 5000
johnmudhead:locktest grant$ rake db:create db:migrate
(in /Users/grant/src/locktest)
== CreateFoos: migrating
=====================================================
-- create_table(:foos)
-> 0.3696s
== CreateFoos: migrated (0.3698s)
============================================
johnmudhead:locktest grant$ script/console
Loading development environment (Rails 2.3.10)
>> f = Foo.create :bar => "AAAAAAAAAAAAAAA!"
=> #<Foo id: 1, bar: "AAAAAAAAAAAAAAA!", created_at: "2010-11-01
19:50:58", updated_at: "2010-11-01 19:50:58">
>> f.save!
=> true
>> exit
johnmudhead:locktest grant$ script/console
Loading development environment (Rails 2.3.10)
>> f = Foo.find(1)
=> #<Foo id: 1, bar: "AAAAAAAAAAAAAAA!", created_at: "2010-11-01
19:50:58", updated_at: "2010-11-01 19:50:58">
>> Foo.transaction do
?> f = Foo.find(1, :lock => true)
>> 1.upto(10000000) { |i| puts i }
>> end
1
2
3
4
...
<<<<<< FROM TERMINAL TWO, WHILE TERMINAL ONE IS STILL COUNTING >>>>>>>>
johnmudhead:Pikimal grant$ cd ../locktest/
johnmudhead:locktest grant$ script/console
Loading development environment (Rails 2.3.10)
>> f = Foo.find(1)
=> #<Foo id: 1, bar: "AAAAAAAAAAAAAAA!", created_at: "2010-11-01
19:50:58", updated_at: "2010-11-01 19:50:58">
>>
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