How to resolve deserialization error in delayed job?

Question

I am trying to use DelayedJob and the job is failing, giving the following error in the database:

{Delayed::DeserializationError
/Library/Ruby/Gems/1.8/gems/delayed_j         


        

Answer 1

There's also a documented bug with DJ when the params passed into the handler field in the DB are longer than a standard TEXT column:

https://github.com/collectiveidea/delayed_job/issues/491

If this happens to be your problem, changing the column to a MEDIUMINT should fix the issue.

I did this in a migration like so:

change_column :delayed_jobs, :handler, :text, :limit => 16777215
ActiveRecord::Base.connection.execute("DELETE FROM delayed_jobs WHERE LENGTH(handler) >= 65535")

You can check to see if it's an issue with a simple DB query:

SELECT * FROM delayed_jobs WHERE LENGTH(handler) >= 65535