Resque正在返回Mysql2 ::错误：关闭MySQL连接：显示来自users
Worker
8608f362-819b-4c15-b42b-69c4df00d27b:1 on low at about 16 hours ago
Class
AddLiveView
Arguments
4383
{"remote_ip"=>"184.72.47.71", "expires"=>true}
Exception
ActiveRecord::StatementInvalid
Error
Mysql2::Error: closed MySQL connection: SHOW FIELDS FROM `users`
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `query'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `block in execute'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract_adapter.rb:244:in `block in log'
/app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.3/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract_adapter.rb:239:in `log'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `execute'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/mysql2_adapter.rb:473:in `columns'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:95:in `block (2 levels) in initialize'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:185:in `with_connection'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:92:in `block in initialize'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:106:in `yield'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:106:in `default'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:106:in `block in initialize'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/base.rb:717:in `yield'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/base.rb:717:in `default'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/base.rb:717:in `columns_hash'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/locking/optimistic.rb:145:in `locking_enabled?'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/relation.rb:110:in `to_a'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/relation/finder_methods.rb:376:in `find_first'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/relation/finder_methods.rb:122:in `first'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/associations/singular_association.rb:42:in `find_target'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/associations/association.rb:146:in `load_target'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/associations/association.rb:56:in `reload'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/associations/singular_association.rb:9:in `reader'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.1.3/lib/active_record/associations/builder/association.rb:41:in `block in define_readers'
/app/app/workers/add_live_view.rb:24:in `block in perform'
/usr/local/lib/ruby/1.9.1/timeout.rb:58:in `timeout'
/app/app/workers/add_live_view.rb:13:in `perform'
我的工人班看起来像：
class AddLiveView
@queue = :low
def self.perform(song_id, options)
begin
song = Song.find(song_id)
current_user = User.find(options['current_user_id']) if !options['expires']
rescue
puts "Error #{$!}"
end
begin
Timeout.timeout(30.seconds) do
if options['expires']
# live_view = LiveView.add_live_view_that_expires(song, options['remote_ip'])
ip_to_country = IpToCountry.where('ip_to_countries.ip_number_to >= INET_ATON(?)', options['remote_ip']).order('ip_number_to ASC').limit(1).first
live_view = LiveView.new(:live_viewable => song, :live_viewable_category => 'View', :expires => true, :expires_at => 1.month.from_now, :ip => options['remote_ip'], :country_name => ip_to_country.country_name, :iso_two_letter_country_code => ip_to_country.iso_two_letter_country_code)
if live_view.save
Pusher["#{song.class.to_s.underscore}_#{song.id}"].trigger('live_view', {
:user => nil,
:live_viewable => live_view.live_viewable,
:artist => live_view.live_viewable.user
})
# We do this in the worker, because we want the live_view object to exist when we push it to our notification service
# Only keep data from last 30 days
LiveView.where('live_views.expires = ? AND live_views.expires_at < ?', true, Date.today).destroy_all
end
else
# ... do something else here ...
end
end
rescue Timeout::Error
end
end
end
在控制台中，我尝试通过以下方式手动执行：
song = Song.find(4383)
ip_to_country = IpToCountry.where('ip_to_countries.ip_number_to >= INET_ATON(?)', '184.72.47.71').order('ip_number_to ASC').limit(1).first
live_view = LiveView.new(:live_viewable => song, :live_viewable_category => 'View', :expires => true, :expires_at => 1.month.from_now, :ip => '184.72.47.71', :country_name => ip_to_country.country_name, :iso_two_letter_country_code => ip_to_country.iso_two_letter_country_code)
live_view.save
live_view.live_viewable.user
一切正常！为什么错误出现在生产中？这可能是因为有很多连接同时命中数据库并且达到了超时限制吗？
答案 0 :(得分：5)
这可能是因为有很多连接同时命中数据库并且达到了超时限制吗？
那可能就是这样。您可以在Rails的控制台中轻松演示类似的东西。
$ rails console
Loading development environment (Rails 3.2.2)
1.9.3-p125 :001 > require 'timeout'
=> true
1.9.3-p125 :002 > Timeout.timeout(1) { User.find_by_sql('SELECT sleep(2) FROM users;') }
User Load (974.4ms) SELECT sleep(2) FROM users;
: execution expired: SELECT sleep(2) FROM users;
ActiveRecord::StatementInvalid: : execution expired: SELECT sleep(2) FROM users;
from /Users/sluukkonen/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.2/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:243:in `query'
# Skip the rest of the backtrace...
在此之后，每次查询数据库都会引发Mysql2 :: Error，因为连接已关闭。
1.9.3-p125 :003 > User.count
Mysql2::Error: closed MySQL connection: SHOW FULL FIELDS FROM `users`
ActiveRecord::StatementInvalid: Mysql2::Error: closed MySQL connection: SHOW FULL FIELDS FROM `users`
from /Users/sluukkonen/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.2/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:243:in `query'
# Again, skip the rest of the backtrace..
我不确定预期的行为是什么，所以我不能说Mysql2或ActiveRecord中是否有错误，但是使用带有pg gem的PostgreSQL并没有表现出类似的行为（后续查询正常执行） 。
将reconnect: true添加到您的database.yml应该可以解决问题，但请注意添加它的caveats。