RuntimeError : Can't add a new key into hash during iteration

[pcodeblooded]

Hi,

Very rarely we are getting Runtime Error. Please help us in finding the solution

class HardWorker < BaseWorker

  sidekiq_options :queue => :default, :retry => 0, :backtrace => true, :failures => :exhausted

  def perform(id)
    ActiveRecord::Base.on_shard(:shard_1) do
        10.times do 
          User.find(rand(1..10))
        end
    end
end

#Trace

~/.rvm/gems/ruby-1.9.3-p547@gemset1/gems/activerecord-2.3.18/lib/active_record/connection_adapters/abstract/connection_pool.rb:296:in `[]='
~/.rvm/gems/ruby-1.9.3-p547@gemset1/gems/activerecord-2.3.18/lib/active_record/connection_adapters/abstract/connection_pool.rb:296:in `establish_connection'
~/.rvm/gems/ruby-1.9.3-p547@gemset1/gems/active_record_shards-2.7.0/lib/active_record_shards/connection_switcher.rb:182:in `establish_shard_connection'
~/.rvm/gems/ruby-1.9.3-p547@gemset1/gems/active_record_shards-2.7.0/lib/active_record_shards/connection_switcher.rb:153:in `switch_connection'
~/.rvm/gems/ruby-1.9.3-p547@gemset1/gems/active_record_shards-2.7.0/lib/active_record_shards/connection_switcher.rb:15:in `on_shard'
~/project/app/workers/hard_worker.rb:6:in `perform'

We are using the active_record_shards gem for sharding the database.

Can we ignore this error ? Since its coming very rarely.

Thanks

[mperham]

Sidekiq has never supported rails 2.3. It's likely a thread safety issue in AR's connection pool.

[pcodeblooded]

Thanks for quicker response. Sorry I forgot to mention, we are trying the #1336 because our project is in rails 2.3.

Is there anything we can patch AR's connection pool to make it thread safe? or you suggest us to upgrade to rails 3.

Thanks

[mperham]

There are reasons Rails 2.3 is not supported; this is one of them. Upgrade or put up with the error.