A Resque plugin. Requires Resque >= 1.10.0 & resque-scheduler >= 1.9.9.
resque-retry provides retry, delay and exponential backoff support for resque jobs.
- Redis backed retry count/limit.
- Retry on all or specific exceptions.
- Exponential backoff (varying the delay between retrys).
- Multiple failure backend with retry suppression & resque-web tab.
- Small & Extendable - plenty of places to override retry logic/settings.
To install:
$ gem install resque-retry
If your using Bundler to manage your dependencies, you should add gem 'resque-retry' to your projects Gemfile.
Add this to your Rakefile:
require 'resque/tasks'
require 'resque_scheduler/tasks'
The delay between retry attempts is provided by resque-scheduler. You'll want to run the scheduler process, otherwise delayed retry attempts will never perform:
$ rake resque:scheduler
Use the plugin:
require 'resque-retry'
class ExampleRetryJob
extend Resque::Plugins::Retry
@queue = :example_queue
@retry_limit = 3
@retry_delay = 60
def self.perform(*args)
# your magic/heavy lifting goes here.
end
end
Then start up a resque worker as normal:
$ QUEUE=* rake resque:work
Now if you ExampleRetryJob fails, it will be retried 3 times, with a 60 second delay between attempts.
For more explanation and examples, please see the remaining documentation.
Lets say your using the Redis failure backend of resque (the default). Every time a job fails, the failure queue is populated with the job and exception details.
Normally this is useful, but if your jobs retry... it can cause a bit of a mess.
For example: given a job that retried 4 times before completing successful. You'll have a lot of failures for the same job and you wont be sure if it actually completed successfully just by just using the resque-web interface.
MultipleWithRetrySuppression is a multiple failure backend, with retry suppression.
Here's an example, using the Redis failure backend:
require 'resque-retry'
require 'resque/failure/redis'
# require your jobs & application code.
Resque::Failure::MultipleWithRetrySuppression.classes = [Resque::Failure::Redis]
Resque::Failure.backend = Resque::Failure::MultipleWithRetrySuppression
If a job fails, but can and will retry, the failure details wont be logged in the Redis failed queue (visible via resque-web).
If the job fails, but can't or won't retry, the failure will be logged in the Redis failed queue, like a normal failure (without retry) would.
If your using the MultipleWithRetrySuppression failure backend, you should
also checkout the resque-web additions!
The new Retry tab displays delayed jobs with retry information; the number of attempts and the exception details from the last failure.
Make sure you include this in your config.ru or similar file:
require 'resque-retry'
require 'resque-retry/server'
# require your jobs & application code.
run Resque::Server.new
Please take a look at the yardoc/code for more details on methods you may wish to override.
Customisation is pretty easy, the below examples should give you some ideas =), adapt for your own usage and feel free to pick and mix!
Retry the job once on failure, with zero delay.
require 'resque-retry'
class DeliverWebHook
extend Resque::Plugins::Retry
@queue = :web_hooks
def self.perform(url, hook_id, hmac_key)
heavy_lifting
end
end
When a job runs, the number of retry attempts is checked and incremented in Redis. If your job fails, the number of retry attempts is used to determine if we can requeue the job for another go.
class DeliverWebHook
extend Resque::Plugins::Retry
@queue = :web_hooks
@retry_limit = 10
@retry_delay = 120
def self.perform(url, hook_id, hmac_key)
heavy_lifting
end
end
The above modification will allow your job to retry up to 10 times, with a delay of 120 seconds, or 2 minutes between retry attempts.
Alternatively you could override the retry_delay method to do something
more special.
Sometimes it is useful to delay the worker that failed a job attempt, but
still requeue the job for immediate processing by other workers. This can be
done with @sleep_after_requeue:
class DeliverWebHook
extend Resque::Plugins::Retry
@queue = :web_hooks
@sleep_after_requeue = 5
def self.perform(url, hook_id, hmac_key)
heavy_lifting
end
end
This retries the job once and causes the worker that failed to sleep for 5 seconds after requeuing the job. If there are multiple workers in the system this allows the job to be retried immediately while the original worker heals itself.For example failed jobs may cause other (non-worker) OS processes to die. A system monitor such as god can fix the server while the job is being retried on a different worker.
@sleep_after_requeue is independent of @retry_delay. If you set both, they
both take effect.
You can override the method sleep_after_requeue to set the sleep value
dynamically.
Use this if you wish to vary the delay between retry attempts:
class DeliverSMS
extend Resque::Plugins::ExponentialBackoff
@queue = :mt_messages
def self.perform(mt_id, mobile_number, message)
heavy_lifting
end
end
Default Settings
key: m = minutes, h = hours
no delay, 1m, 10m, 1h, 3h, 6h
@backoff_strategy = [0, 60, 600, 3600, 10800, 21600]
The first delay will be 0 seconds, the 2nd will be 60 seconds, etc... Again, tweak to your own needs.
The number of retries is equal to the size of the backoff_strategy
array, unless you set retry_limit yourself.
The default will allow a retry for any type of exception. You may change
it so only specific exceptions are retried using retry_exceptions:
class DeliverSMS
extend Resque::Plugins::Retry
@queue = :mt_messages
@retry_exceptions = [NetworkError]
def self.perform(mt_id, mobile_number, message)
heavy_lifting
end
end
The above modification will only retry if a NetworkError (or subclass)
exception is thrown.
You may also want to specify different retry delays for different exception
types. You may optionally set @retry_exceptions to a hash where the keys are
your specific exception classes to retry on, and the values are your retry
delays in seconds or an array of retry delays to be used similar to
exponential backoff.
class DeliverSMS
extend Resque::Plugins::Retry
@queue = :mt_messages
@retry_exceptions = { NetworkError => 30, SystemCallError => [120, 240] }
def self.perform(mt_id, mobile_number, message)
heavy_lifting
end
end
In the above example, Resque would retry any DeliverSMS jobs which throw a
NetworkError or SystemCallError. If the job throws a NetworkError it
will be retried 30 seconds later, if it throws SystemCallError it will first
retry 120 seconds later then subsequent retry attempts 240 seconds later.
You may define custom retry criteria callbacks:
class TurkWorker
extend Resque::Plugins::Retry
@queue = :turk_job_processor
@retry_exceptions = [NetworkError]
retry_criteria_check do |exception, *args|
if exception.message =~ /InvalidJobId/
false # don't retry if we got passed a invalid job id.
else
true # its okay for a retry attempt to continue.
end
end
def self.perform(job_id)
heavy_lifting
end
end
Similar to the previous example, this job will retry if either a
NetworkError (or subclass) exception is thrown or any of the callbacks
return true.
Use @retry_exceptions = [] to only use callbacks, to determine if the
job should retry.
You may override args_for_retry, which is passed the current
job arguments, to modify the arguments for the next retry attempt.
class DeliverViaSMSC
extend Resque::Plugins::Retry
@queue = :mt_smsc_messages
# retry using the emergency SMSC.
def self.args_for_retry(smsc_id, mt_message)
[999, mt_message]
end
self.perform(smsc_id, mt_message)
heavy_lifting
end
end
The retry attempt is incremented and stored in a Redis key. The key is
built using the retry_identifier. If you have a lot of arguments or really long
ones, you should consider overriding retry_identifier to define a more precise
or loose custom retry identifier.
The default retry identifier is just your job arguments joined with a dash -.
By default the key uses this format:
resque-retry:<job class name>:<retry_identifier>.
Or you can define the entire key by overriding redis_retry_key.
class DeliverSMS
extend Resque::Plugins::Retry
@queue = :mt_messages
def self.retry_identifier(mt_id, mobile_number, message)
"#{mobile_number}:#{mt_id}"
end
self.perform(mt_id, mobile_number, message)
heavy_lifting
end
end
- Yes please!
- Fork the project.
- Make your feature addition or bug fix.
- Add tests for it.
- Commit.
- Send me a pull request. Bonus points for topic branches.
- If you edit the gemspec/version etc, do it in another commit please.