I applied "mongoid-locker" gem on my app but during concurrent request it got failed and got error "LockError: could not get lock".So can anyone help me out.
By default, with_lock does not wait for other locks to complete, so if you actually have a concurrent access, you will get the LockError raised if you don't tell it to wait.
Try it like so:
object = Object.first
object.with_lock wait:true do
object.foo = "bar"
object.save!
end
Related
I use a Sidekiq queue to process communications with an unreliable, 3rd party API. Since this API is often down for a couple minutes at a time and then back up again, Sidekiq has been handy. When a connection issue happens, an error is raised and Sidekiq throws the job back in the queue to be retried again later, after some time has passed.
I use NewRelic to not only help debug crashes, but also for monitoring. My problem is that this current methodology above creates errors in NewRelic. If the 3rd party API is down for more than a couple of minutes, the error count accumulates enough to cause notifications to send out through NewRelic.
What I'd like to do is only raise an error from my worker when a certain number of retries have occurred for a job. I'm using sidekiq_retries_exhausted to do this. My problem is that I'm not quite sure how to put jobs back in the queue after they have an error without raising an error.
Does Sidekiq provide any facilities to return a job to a queue, increment the number of retries for the job, and have it sit there until it's due to run again, as if an exception was raised in the worker class?
You raise a specific error and tell the error service to ignore errors of that type. For NewRelic:
https://docs.newrelic.com/docs/agents/ruby-agent/installation-configuration/ruby-agent-configuration#error_collector.ignore_errors
Here is what I did to keep intentional retry errors out of AirBrake:
class TaskWorker
include Sidekiq::Worker
class RetryNotAnError < RuntimeError
end
def perform task_id
task = Task.find(task_id)
task.do_cool_stuff
if task.finished?
#log.debug "Task #{task_id} was successful."
return false
else
#log.debug "Task #{task_id} will try again later."
raise RetryNotAnError, task_id
end
end
end
Tell Airbrake to ignore it:
Airbrake.configure do |config|
config.ignore << 'RetryNotAnError'
end
It's good to make your exception name OBVIOUSLY not an error (e.g. RetryLaterNotAnError), as it will still show up in logs and such, and you don't want to freak people out when they see a bunch of them.
ps. That said, I would really like to see Sidekiq to provide an explicit, errorless retry mechanism.
If using Sidekiq Enterprise, one other option might be to utilize the optional set of additional error types that will then get treated as Sidekiq::Limiter::OverLimit violations.
For my purposes, I've used a new error class and then added it to the list in the config. Here are the notes from the sidekiq-ent code (not in the public sidekiq repo) on how to modify your config file:
# An optional set of additional error types which would be
# treated as a rate limit violation, so the job would automatically
# be rescheduled as with Sidekiq::Limiter::OverLimit.
#
# Sidekiq::Limiter.errors << MyApp::TooMuch
# Sidekiq::Limiter.errors = [Foo::Error, MyApp::Limited]
Inside the specific job you can specify the max_retries, or it will default to 20:
sidekiq_options max_limiter_retries: 10
Inside the job, I'll rescue the "expected" intermittent error that I'd rather not ignore completely and then raise the error I've added to the list, something like this:
rescue RestClient::RequestTimeout => e
raise SidekiqSoftRetry.new(e.inspect)
end
Here's what that looks like in my initialization file-- and Mike Perham was kind enough to respond with the option to update the global retry limit.
class SidekiqSoftRetry < RuntimeError
end
Sidekiq::Limiter::DEFAULT_OPTIONS[:reschedule] = 10
Sidekiq::Limiter.configure do |config|
config.errors.concat(
[
SidekiqSoftRetry,
]
)
end
I am trying to run a rake task to get all the data with a specific tag from Instagram, and then input some of the data into my server.
The task runs just fine, except sometimes I'll get an error response. It's sort of random, so I think it just happens sometimes, and since it's a fairly long running task, it'll happen eventually.
This is the error on my console:
Instagram::BadGateway: GET https://api.instagram.com/v1/tags/xxx/media/recent.json?access_token=xxxxx&max_id=996890856542960826: 502: The server returned an invalid or incomplete response.
When this happens, I don't know what else to do except run the task again starting from that max_id. However, it would be nice if I could get the whole thing to automate itself, and retry itself from that point when it gets that error.
My task looks something like this:
task :download => :environment do
igs = Instagram.tag_recent_media("xxx")
begin
sleep 0.2
igs.each do |ig|
dl = Instadownload.new
dl.instagram_url = ig.link
dl.image_url = ig.images.standard_resolution.url
dl.caption = ig.caption.text if ig.caption
dl.taken_at = Time.at(ig.created_time.to_i)
dl.save!
end
if igs.pagination.next_max_id?
igs = Instagram.tag_recent_media("xxx", max_id: igs.pagination.next_max_id)
moreigs = true
else
moreigs = false
end
end while moreigs
end
Chad Pytel and Tammer Saleh call this "Fire and forget" antipattern in their Rails Antipatterns book:
Assuming that the request always succeeds or simply not caring if it
fails may be valid in rare circumstances, but in most cases it's
unsufficient. On the other hand, rescuing all the exceptions would be
a bad practice aswell. The proper solution would be to understand the
actual exceptions that will be raised by external service and rescue
those only.
So, what you should do is to wrap your code block into begin/rescue block with the appropriate set of errors raised by Instagram (list of those errors can be found here). I'm not sure which particular line of your code snippet ends with 502 code, so just to give you and idea of what it could look like:
begin
dl = Instadownload.new
dl.instagram_url = ig.link
dl.image_url = ig.images.standard_resolution.url
dl.caption = ig.caption.text if ig.caption
dl.taken_at = Time.at(ig.created_time.to_i)
dl.save!
rescue Instagram::BadGateway => e # list of acceptable errors can be expanded
retry # restart from beginning
end
I'm having an issue trying to get a timeout when connecting via TCPSocket to a remote resource that isn't available. It just hangs indefinitely without timing out. Ideally I'd want it to try reconnect every 2 minutes or so, but the TCPSocket.new call seems to block. I've tried using timeout() but that doesn't do anything either. Trying the same call in an IRB instance works perfectly fine, but when it's in Rails, it fails. Anyone have a work around for this?
My code looks something as follows:
def self.connect!
##connection = TCPSocket.new IP, 4449
end
def self.send(cmd)
puts "send "
unless ##connection
self.connect!
end
loop do
begin
##connection.puts(cmd)
return
rescue IOError
sleep(self.get_reconnect_delay)
self.connect!
end
end
end
Unfortunately, there is currently no way to set timeouts on TCPSocket directly.
See http://bugs.ruby-lang.org/issues/5101 for the feature request. You will have use the basic Socket class and set socket options.
Our app is hosted on heroku and we use delayed job when sending info to a remote system (via a GET to a url with some url params)
the remote system returns a success code usually, but it it;s real busy it returns a tryagain code.
suppose the our method is
def send_info
the_url = "http://mydomain.com/dosomething?arg=#{self.someval}"
the_result = open(the_url).read
successflag = get_success_flag_from(the_result)
end
and so somewhere in our code we do
#widget.delay.send_info
and that all works fine.
Except it does not automatically handle the case where the remote said to try back later.
Is there any way for the send_info method (which is what delayed job will execute) to "tell" delayed_job "retry me again"? Do we need to throw some custom exception or something?
Raising any kind of exception ought to cause delayed_job to requeue it (subject to only-trying-so-many-times); if you don't especially need a custom exception you can just raise a RuntimeError.
This question already has an answer here:
Overriding/Modifying Rails Class (ActiveResource)
(1 answer)
Closed 3 years ago.
I'm trying to contact a REST API using ActiveResource on Rails 2.3.2.
I'm attempting to use the timeout functionality so that if the resource I'm contacting is down I can fail quickly - I'm doing this with the following:
class WorkspaceResource < ActiveResource::Base
self.timeout = 5
self.site = "http://mysite.com/restAPI"
end
However, when I try to contact the service when I know it isn't available, the class only times out after the default 60 seconds. I can see from the error stack that the timeout error does indeed come from an ActiveResource class in my gem folder that has the proper functions to allow timeout settings, but my set timeout never seems to work.
Any thoughts?
So apparently the issue is not that timeout is not functioning. I can run a server locally, make it not return a response within the timeout limit, and see that timeout works.
The issue is in fact that if the server does not accept the connection, timeout does not function as I expected it to - it doesn't function at all. It appears as though timeout only works when the server accepts the connection but takes too long to respond.
To me, this seems like an issue - shouldn't timeout also work when the server I'm contacting is down? If not, there should be another mechanism to stop a bunch of requests from hanging...anyone know of a quick way to do this?
The problem
If you're running on Ruby 1.8.x then the problem is its lack of real system threads.
As you can read first hereand then here, there are systemic problems with timeouts in Ruby. An interesting discussion but for you in particular some comments suggest that the timeout is effectively ignored and defaults to 60 seconds - exactly what you are seeing.
Solutions ...
I have a similar issue with our own product when trying to send emails - if the email server is down the thread blocks. For me the solution was to spin the request off on a separate thread and therefore my main request-processing thread doesn't block.
There are non-blocking libraries out there for Ruby but perhaps you could take a look first at this System Timeout Gem.
An option open to anyone using Rails behind a proxy like nginx would be to set the upstream timeout to a lower number - that way you'll get notified if the server is taking too long. I'd only do this if I were really stuck for a solution.
Last but not least, it's possible that running Rails 2.3.2 on top of Ruby 1.9.1 will fix the issue.
Alternatively, you could try to catch these connection errors and retry once (after certain period of time) just to make sure the connection is really out.
retried = false
begin
#businesses = Business.find(:all, :params => { :shop_domain => #shop.domain })
retried = false
rescue ActiveResource::TimeoutError => ex
#raise ex
rescue ActiveResource::ConnectionError, ActiveResource::ServerError, ActiveResource::ClientError => ex
unless retried
sleep(((ex.respond_to?(:response) && ex.response['Retry-After']) || 5).to_i)
retried = true
retry
else
# raise ex
end
end
Inspired by this solution from Shopify for paginating a large number of records. https://ecommerce.shopify.com/c/shopify-apis-and-technology/t/paginate-api-results-113066