Testing mysql2 wait_timeout param

mysql2_wait_timeout.rb

require 'rubygems'
gem 'mysql2'
gem 'activerecord', '3.1.1'
require 'active_record'

# http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html#sysvar_wait_timeout
MYSQL_WAIT_TIMEOUT_MAX = 2147483

# Testing the remote db connection after a 60s sleep
def test_connection(extra_conf = {})
  conf = {
    :host => "1.2.3.4",
    :username => "root",
    :database => "test",
    :adapter  => "mysql2"
  }
  ActiveRecord::Base.establish_connection(conf.merge(extra_conf))
  puts ActiveRecord::Base.connection.execute("SHOW VARIABLES LIKE \"wait_timeout\"").to_a.join(" : ")
  sleep 60
  puts ActiveRecord::Base.connection.active? ? "Connection up !" : "Connection lost !"
end

test_connection(:wait_timeout => MYSQL_WAIT_TIMEOUT_MAX)
test_connection(:wait_timeout => MYSQL_WAIT_TIMEOUT_MAX + 1)

output

$ ruby mysql2_wait_timeout.rb
wait_timeout : 2147483
Connection up !
wait_timeout : 2147484
Connection lost !

I am having same issue ? did you end up submitting a bug report to rails ? if not I will.
I have spend some time trying to find who is changing it.

I do have some news for you.
when you set it to MAX + 1. it actually uses mysql default which is 28800, which is , I suspect, 28 seconds. mysql docs says it should be seconds but i think its treating it as milliseconds.
What OS did you use to reproduce this ? i am on FreeBSD.

Cheers,

Yes I did submit a pull request to rails about this issue.
My conclusions are the same as yours... mysql2 sets the wait_timeout param with a too high value by default. But my pull request didn't have much success, probably because we're very few to face this problem. My DB is on FreeBSD too (and I tested it with a client app on FreeBSD and OS X : same behavior). So It's probably FreeBSD + MySQL related...
I'm glad that my investigation on this subject was useful for someone !

More interesting news.
it has nothing to do with FreeBSD.
for some reason in MySQL 5.5x wait_timeout is in milliseconds, but in MySQL 5.1x its in seconds ( as per documentation )
I have confirmed this on Linux and FreeBSD

still investigating...

I'm having this same issue. Anyone that has success to fix that?

hi guys,
just one more little discovery,
this has been fixed in mysql 5.6

link? re: mysql 5.6 fix

No particular link.just install MySQL 5.6 which has been released a while ago.
In production systems I will stick with 5.1

Please mind that the actual limit for wait_timeout depends on the operating system you are using. The individual values can be retrieved from the MySQL documentation (links v.5.6).

Another point is that I cannot find wait_timeout in Rails 3.2.14 while there are configuration options in Rails 4. I wonder if I am actually able to pass the setting via database.yml.