I have a sidekiq worker that waits for a change to happen to a record made by a remote client. Something like the following:
#myworker async process to wait for client to confirm status
perform(myRecordID)
sendClient(myRecordID)
didClientAcknowledge = false
while !didClientAcknowledge
didClientAcknowledge = myRecords.find(myRecordID).status == :ACK_OK
if didClientAcknowledge
break
end
# wait for client to perform an update on the record to confirm status
sleep 5.seconds
end
Rails.logger.info("client got the message")
end
my problem is that although I can see that the client has in fact performed the acknowledgement and updated the record with correct status update (ACK_OK), my sidekiq thread continues to see the old status for myRecord.
I'm sure my logic is flawed here but it seems like the sidekiq process does not "see" changes to the DB...but if I used my rails console I can see that the client has in fact updated the DB as expected...
Thanks!
Edit 1
ok so here's a thought, instead of the loop, I'll schedule another call to the worker within 5 seconds... so here's the updated code:
perform(myRecordID, retry_count)
retry_count -= 1
if retry_count < 1
return
end
sendClient(myRecordID)
didClientAcknowledge = false
if !didClientAcknowledge
didClientAcknowledge = myRecords.find(myRecordID).status == :ACK_OK
if didClientAcknowledge
Rails.logger.info("client got the message")
return
end
# wait for client to perform an update on the record to confirm status
myWorker.perform_in(5.seconds)
end
Rails.logger.info("client got the message")
end
This seems to work, but will test a bit more..one challenge is having a retry count which means I need to maintain some sort of variable between calls to the worker...
edit2 possibly this can be done by passing in the time to the first call and then checking if a timeout has been surpassed before invoking the next instance...assuming time does not stand still as well inside the async call...
edit3 Adding the retry_count argument allows us to control how many times this worker will be spawned...
Related
I use a timeout to perform an action periodically. Sometimes the timeout interval needs to be modified, so I set a new timeout and then destroy the old one by returning False from the callback. However, I have gotten bug reports that seem to pretty clearly show that sometimes the initial timer is not destroyed because the actions are running at both the old and new timeout intervals. Can you think of any reason this could happen? It seems to be an infrequent occurrence and I can not duplicate it.
Here's my python code for the callback function. There's essentially nothing happening between when I create the new timer (which succeeds) and when I return False (which seems to sometimes, rarely, fail to destroy the original timer).
Since this code was written I have modified it to store the timeout return value and to use GLib.SOURCE_CONTINUE and GLib.SOURCE_REMOVE instead of True/False, but that version has not been deployed yet. Nevertheless, I don't think those changes should be relevant here.
def on_interval_timeout(self, user_data):
# perform action here
# update timeout if required
if self.update:
interval = (self.model.props["interval-min"] * 60 +
self.model.props["interval-sec"])
GLib.timeout_add_seconds(interval, self.on_interval_timeout, None)
self.update = False
return False
return True
So I'm building a website that calls a third-party API that can take from 20 seconds to 30 minutes to return a result. But I can't know this duration in advance so need to poll it frequently to check if the work is done (returns "COMPLETE" and the result) or not (returns "IN_PROGRESS"). Also, this API might be called many times from many users at the same time.
So I created a Sidekiq worker that checks the API every 5 seconds until it receives "COMPLETE", and only then it ends. But I've read that Sidekiq should only be doing short-lived jobs, and I'm struggling to get my head around how should I do it. Also I've been trying to search for an answer but I suspect I don't know the words to find what I'm looking for.
I'm sure there is a way I can tell my workers to call the API once, and if the result is "IN_PROGRESS" end but make sure another worker will do another API call to check, and so on and so on until the result is "COMPLETE".
Also, I guess this is also handy to better distribute the load in case many users demand the use of said API, because fewer workers can do more of this short-lived jobs.
This is my worker, which I hope clarifies what I'm doing right now:
class ThingProgressWorker
include Sidekiq::Worker
def perform(id)
#thing = Thing.find(id)
#thing_api_call = ThingAPICall.new // This uses the ruby library of the API
completed = false
while completed == false
result = #thing_api_call.get_result( { thing_job_name: #thing.job_name })
if !result.include? "COMPLETED"
completed = false
sleep 5
else
completed = true
#thing.status = "completed"
#thing.save
break
end
end
end
end
So if the API takes ten minutes to go from "IN_PROGRESS" to "COMPLETED" this worker will be busy for that long, which I recon is not advised at all.
I've been thinking about this for some hours now and can't think of how should I do to make each API call its own job without having a worker busy until the API is done.
The only solution I've thought so far is having a master worker that calls another worker for each API call, but then I'll still have a worker busy for as long as the API takes to send the result.
I'd appreciate any help or directions!
Thanks in advance
Try to call the worker with a delay. for example:
class ThingProgressWorker
include Sidekiq::Worker
def perform(id)
#thing = Thing.find(id)
#thing_api_call = ThingAPICall.new // This uses the ruby library of the API
result = #thing_api_call.get_result( { thing_job_name: #thing.job_name })
if !result.include? "COMPLETED"
ThingProgressWorker.perform_in(1.minute, id)
else
completed = true
#thing.status = "completed”
#thing.save
end
end
end
This will add the worker to the queue but will not run it immediately but in the time you specify.
I am trying to build quizup like app and want to send broadcast every 10 second with a random question for 2 minutes. How do I do that using rails ? I am using action cable for sending broadcast. I can use rufus-scheduler for running an action every few seconds but I am not sure if it make sense to use it for my use case .
Simplest solution would be to fork a new thread:
Thread.new do
duration = 2.minutes
interval = 10.seconds
number_of_questions_left = duration.seconds / interval.seconds
while(number_of_questions_left > 0) do
ActionCable.server.broadcast(
"some_broadcast_id", { random_question: 'How are you doing?' }
)
number_of_questions_left -= 1
sleep(interval)
end
end
Notes:
This is only a simple solution of which you are actually ending up more than 2.minutes of total run time, because each loop actually ends up sleeping very slightly more than 10 seconds. If this discrepancy is not important, then the solution above would be already sufficient.
Also, this kind-of-scheduler only persists in memory, as opposed to a dedicated background worker like sidekiq. So, if the rails process gets terminated, then all currently running "looping" code will also be terminated as well, which you might intentionally want or not want.
If using rufus-scheduler:
number_of_questions_left = 12
scheduler = Rufus::Scheduler.new
# `first_in` is set so that first-time job runs immediately
scheduler.every '10s', first_in: 0.1 do |job|
ActionCable.server.broadcast(
"some_broadcast_id", { random_question: 'How are you doing?' }
)
number_of_questions_left -= 1
job.unschedule if number_of_questions_left == 0
end
In a normal test using human and browser, everything is work as expected. However, when I use rspec, I can see that I have:
D, [2014-08-16T13:48:09.510013 #19418] DEBUG -- : SQL (0.6ms) UPDATE "system_flights_cacheds" SET "client_stuff" = '{"captcha":"656556"}' WHERE "system_flights_cacheds"."guid" = '5647046e-4194-498e-a0d7-512614b147d8'
But I cannot believe that actually my database record is not updated. Previously I used .save, but with no success in fact it creates SAVEPOINT.
My code in trouble is basically an API endpoint:
cache = System::Flights::Cached.search_cache options
# update database, when the captcha is present. this way, the worker
# when updating the database can see the changes and act accordingly!
if cache && params[:captcha]
# remember, anyone can (basically) see the captcha. thus,
# this is a bit paranoid, only allow captcha update
# if the user is same! in the json, if not forgotten,
# captcha is only displayed when the user_id is equal
server_stuff = cache.server_stuff.with_indifferent_access
if server_stuff[:user_id] == current_user.id
cache.time_renewed = 10
cache.client_stuff_will_change!
cache.client_stuff ||= {}
cache.client_stuff[:captcha] = params[:captcha]
# cache.save!
cache.update_columns(client_stuff: cache.client_stuff)
end
else
# only spawn worker if there is no captcha parameter passed
spawn_search_worker({user_id: current_user.id, options: options})
end
The client can reach this anytime and it will span worker. When a new record is already in database but is_processed is false, the worker will quit. Thus, calling this multiple times will be ok as also be a means to check status if the work is done or not.
The worker will wait the client to enter for a captcha. So, we have class like WaitableLogin, that do basically:
max_repeat = 3 # 14
# annul flag, if set to true, the data will not get persisted.
annul = false
while max_repeat > 0
# interval of 5 secs that worker can check the database
sleep 5
max_repeat -= 1
# break if captcha already entered by client
# seek from the database if the client has posted
# the captcha text
cache = System::Flights::Cached.search_cache options
client_stuff = nil
client_stuff = cache.client_stuff.with_indifferent_access if cache && cache.client_stuff
if client_stuff && client_stuff[:captcha]
captcha_text = client_stuff[:captcha]
airline.fill_captcha(captcha_text).finalize_login
puts "SOMEHOW I AM HERE: #{captcha_text}"
# remove all server's stuff
cache.server_stuff_will_change!
cache.server_stuff.clear
cache.save!
annul = airline.in_login_page?
end
end
So, WaitableLogin will check if the client_stuff is updated. If it is, then we know that client has submitted the captcha (through the Endpoint, the worker will check if captcha is a param and will update the database if there's captcha field).
The control then transferred back to the Worker. You can see that there's a lot of code that use cache at many parts of the codes across files, cache is just variable name nothing to do with its semantic meaning in Rails or whatever.
When I run normally on browser, I don't see any problem. In fact, no SAVEPOINT even if I use .save. I thought, it is creating some bug somewhere with that SAVEPOINT so I decided to try using .update_columns. But, again, with no success.
This is what the test looks like
before(:each) do
System::Flights::Cached.delete_all
end
describe "requests" do
it "should process 2a1c1i" do
cached = nil
post("/api/v1/x.json", {
access_token: CommonFlightData::ACCESS_TOKEN,
business_token: CommonFlightData::BUSINESS_TOKEN,
captcha: ""
}.merge!(CommonFlightData.oneway_1a(from: "8-9-2014")))
puts "enter the captcha: "
captcha = STDIN.gets.chomp
puts "Entered: #{captcha}"
post("/api/v1/x.json", {
access_token: CommonFlightData::ACCESS_TOKEN,
business_token: CommonFlightData::BUSINESS_TOKEN,
captcha: captcha
}.merge!(CommonFlightData.oneway_1a(from: "8-9-2014")))
sleep 10
SO what am I missing at, I tired. No error raised. When I check .inspect after update_columns, it seems all is updated. But, when you see at the database, nothing is updated.
EDIT: I put lock_version so that I have optimistic locking (by default, I think). And turn out, as expected, it was set to 2.
EDIT 2: If I command an edit from a rails console at the time when the code asking for captcha, IT UPDATES the data. SO, why the RSpec spec that run the api endpoint to submit a captcha won't update the row. All real-life no spec-in-origin code is finely executed.
I have trying to save a new record with delayed job. The code in question is below:
#method being called:
ibo.add_to_database(params[:url])
#method definition
def add_to_database(url)
feed = Feeds.new do |f|
f.url = url
f.title = self.feed_title if self.feed_title
f.link = self.site_link if self.site_link
f.image = self.feed_image if self.feed_image
end
feed.save!
end
handle_asynchronously :add_to_database
I get absolutely no errors, and the job is removed from the database as it should be. Except there is no change to the Feeds model. Anyone have any ideas what gives?
delayed_job runs as a daemon thread, so the first thing to do would be to check whether that it is running:
ps ax | grep delayed_job
the next thing I would check the log of actual delayed job, it would probably have you error description:
less log/delayed_job.log
Other then that, your code sniplet looks fine.