Delayed job not executed despite disappearing from delayed_jobs table immediately - ruby-on-rails-3

Question

I implemented a delayed job in my Rails application, following the instructions.
I start the Rails app
I click on a link that launches the delayed job
The job is visible in the database's delayed_jobs table
I run rake jobs:work
The job disappears from the table, so I guess the job has been performed
BUT PROBLEM: /tmp/job.log has not been written (what the job should have done)
The job:
class CsvImportJob
def perform
File.open('/tmp/job.log', 'w') {|f| f.write("Hello") }
end
end
The call:
job = CsvImportJob.new
job.delay.perform
Nothing in the logs.
The rake jobs:work terminal says nothing after its start message:
[Worker(host:nico pid:25453)] Starting job worker
Nothing happen either when I launch the job while rake jobs:work is running.
In contrast, when the line "hello".delay.length is executed, delayed_jobs processes it and a message String#length completed after 0.0556 - 1 jobs processed at 3.6912 j/s, 0 failed does appear.

Answer 1

See https://github.com/collectiveidea/delayed_job/wiki/Common-problems#wiki-undefined_method_xxx_for_class in documentation.
Even delayed_job author don't know the reason. It somehow depends on the webserver you run in on. Try the wiki's recommendation.
See also delayed_job: NoMethodError

Answer 2

I'm a little late to the party, but also look at:
https://github.com/collectiveidea/delayed_job/wiki/Common-problems#wiki-jobs_are_silently_removed_from_the_database
Your case doesn't sound like a YAML deserialization error, but (as the WIKI suggests), you might set Delayed::Worker.destroy_failed_jobs = false so the failed job stays in the table and you can examine the cause of the error.
update
As I think about it: are you sure that the CsvImportJob class is known to the worker task? That is, is csv_import_job.rb defined in one of the "well known" directories for a Rails class? If not, then the worker task won't be able to de-serialize it, which will lead to exactly the behavior that you're seeing.
If for some reason, cav_import_job.rb is not in a well known directory, you can always require it from an initialization file -- that should fix the problem.