How do You monitor sidekiq processes? - ruby

I'm working on a production app that has multiple rails servers behind nginx loadbalancer. We are monitoring sidekiq processes with monit, and it works just fine - when sidekiq proces dies monit starts it right back.
However recently encountered a situation where one of these processes was running and visible to monit, but for some reason not visible to sidekiq. That resulted in many failed jobs and took us some time to notice that we're missing one process in sidekiq Web UI, since monit was telling us everything was fine and all processes were running. Simple restart fixed the problem.
And that bring me to my question: how do you monitor your sidekiq processes? I know i can use something like rollbar to notify me when jobs fail, but i'd like to know if there is a way to monitor process count and preferably send mail when one dies. Any suggestions?
Something that would ping sidekiq/stats and verify response.

My super simple solution to a similar problem looks like this:
# sidekiq_check.rb
namespace :sidekiq_check do
task rerun: :environment do
if Sidekiq::ProcessSet.new.size == 0
exec 'bundle exec sidekiq -d -L log/sidekiq.log -C config/sidekiq.yml -e production'
end
end
end
and then using cron/whenever
# schedule.rb
every 5.minutes do
rake 'sidekiq_check:rerun'
end

We ran into this problem where our sidekiq processes had stopped working off jobs overnight and we had no idea. It took us about 30 minutes to integrate http://deadmanssnitch.com by following these instructions.
It's not the prettiest or cheapest option but it gets the job done (integrates nicely with Pagerduty) and has saved our butt twice in the last few months.
On of our complaints with the service is the shortest grace interval we can set is 15 minutes which is too long for us. So we're evaluating similar services like Healthchecks, etc.

My approach is the following:
create a background job that does something
call the job regularly
check that the thing is being done!
so; using a cron script (or something like whenever) every 5 mins, I run :
CheckinJob.perform_later
It's now up to sidekiq (or delayed_job, or whatever active job you're using) to actually run the job.
The job just has to do something which you can check.
I used to get the job to update a record in my Status table (essentially a list of key/value records). Then I'd have a /status page which returns a :500 status code if the record hasn't been updated in the last 6 minutes.
(obviously your timing may vary)
Then I use a monitoring service to monitor the status page! (something like StatusCake)
Nowdays I have a simpler approach; I just get the background job to check in with a cron monitoring service like
IsItWorking
Dead Mans Snitch
Health Checks
The monitoring service which expects your task to check in every X mins. If your task doesn't check in - then the monitoring service will let you know.
Integration is dead simple for all the services. For Is It Working it would be:
IsItWorkingInfo::Checkin.ping(key:"CHECKIN_IDENTIFIER")
full disclosure: I wrote IsItWorking !

I use god gem to monitor my sidekiq processes. God gem makes sure that your process is always running and also can notify the process status on various channels.
ROOT = File.dirname(File.dirname(__FILE__))
God.pid_file_directory = File.join(ROOT, "tmp/pids")
God.watch do |w|
w.env = {'RAILS_ENV' => ENV['RAILS_ENV'] || 'development'}
w.name = 'sidekiq'
w.start = "bundle exec sidekiq -d -L log/sidekiq.log -C config/sidekiq.yml -e #{ENV['RAILS_ENV']}"
w.log = "#{ROOT}/log/sidekiq_god.log"
w.behavior(:clean_pid_file)
w.dir = ROOT
w.keepalive
w.restart_if do |restart|
restart.condition(:memory_usage) do |c|
c.interval = 120.seconds
c.above = 100.megabytes
c.times = [3, 5] # 3 out of 5 intervals
end
restart.condition(:cpu_usage) do |c|
c.interval = 120.seconds
c.above = 80.percent
c.times = 5
end
end
w.lifecycle do |on|
on.condition(:flapping) do |c|
c.to_state = [:start, :restart]
c.times = 5
c.within = 5.minute
c.transition = :unmonitored
c.retry_in = 10.minutes
c.retry_times = 5
c.retry_within = 1.hours
end
end
end

Related

Sidekiq multiple workers?

I have a question regarding Sidekiq. I come from the Resque paradigm, and in the current application I launch one worker per queue, so in the terminal I would do:
rake resque:work QUEUE='first'
rake resque:work QUEUE='second'
rake resque:work QUEUE='third'
Then, If I want more workers, for example for the third queue, I just create more workers as:
rake resque:work QUEUE='third'
My question is...
With Sidekiq, how would you start with multiple workers? I know you can do this:
sidekiq -q first, -q second, -q third
But that would just start one worker that fetches all those queues. So, how would I go to start three workers, and tell each worker to just focus on a particular queue? Also, how would I do that in Heroku?
You could use a config file in config/sidekiq.yml :
# Sample configuration file for Sidekiq.
# Options here can still be overridden by cmd line args.
# sidekiq -C config.yml
---
:verbose: true
:pidfile: ./tmp/pids/sidekiq.pid
:concurrency: 15
:timeout: 5
:queues:
- [first, 20]
- [second, 20]
- [third, 1]
staging:
:verbose: false
:concurrency: 25
production:
:verbose: false
:concurrency: 50
:timeout: 60
That way you can configure exactly what you want, and to answer precisely your question the concurrency value is what you are loking for, it defines the number of concurrent workers executed.
More info here : https://github.com/mperham/sidekiq/wiki/Advanced-Options
So, how would I go to start three workers, and tell each worker to
just focus on a particular queue?
You can define on the worker-level in which queue it should be placed via sidekiq_options.
To place for example your worker in a queue called "first" just define it with
class MyWorker
include Sidekiq::Worker
sidekiq_options :queue => :first
...
end

Set Process Start Sequence with God Gem

Is it possible to have God start two processes in sequence?
I am using Sidekiq which relies on Redis. I would like to start up Redis, then start up Sidekiq, and I have two separate watches set up which work fine independently, however when I run:
$ god -c "./config.god" -D
It seems that God tries to launch both simultaneously, resulting in errors from Sidekiq because it can't connect to the Redis server.
My config file for God is below:
# config.god
PROJECT_ROOT = ENV['PROJECT_ROOT'] || "/Path/to/app"
God.watch do |w|
w.name = "redis-server"
w.group = 'conversion-api'
w.interval = 30.seconds
w.start = "/usr/local/Cellar/redis/2.4.16/bin/redis-server"
end
God.watch do |w|
w.name = "sidekiq"
w.group = 'conversion-api'
w.interval = 20.seconds
w.dir = ENV['PROJECT_ROOT']
w.start = "bundle exec sidekiq -v -C #{PROJECT_ROOT}/config.yml -r #{PROJECT_ROOT}/app.rb -c 10"
w.stop = "bundle exec sidekiqctl stop #{PROJECT_ROOT}/tmp/pids/sidekiq.pid 5"
w.keepalive
# Don't pass in a pid file location. Let God handle things. Leaving a pid file location in
# the sidekiq config.yml seems to be harmless though and it lets us force stop sidekiq independently
# of God.
# w.pid_file = File.join(PROJECT_ROOT, 'tmp/pids/sidekiq.pid')
w.log = "./log/god_sidekiq.log"
w.behavior(:clean_pid_file)
end
I also, was wondering about controlling startup order. I started looking at the possibility of using the watch transition methods on the sidekiq watch object and checking if the redis process was running: via possibly God.watches["redis"].state == :up and then start sidekiq. Ran out of time and just placed a hack of "sleep 5;" before the sidekiq start and before the redis shutdown.

Is it possible to have one Unicorn child process a queue, whilst the rest process web requests on Heroku single Dyno?

If you have Unicorn set up on a single dyno on Heroku, say with 3 workers.
Is it possible to have 2 of the child workers processing web requests, and 1 Unicorn child doing background jobs, such as a resque queue, or scheduled tasks?
Or is that just not appropriate?
Now got it Working!
OK, so using the answer bellow I managed to get it to pick up the cue, but it took a bit of tinkering first. This is what worked for me.
Procfile
web: bundle exec unicorn_rails -p $PORT -c config/unicorn.rb
unicorn.rb
worker_processes 2
preload_app true
timeout 30
#resque_pid = nil
before_fork do |server, worker|
#resque_pid ||= spawn("bundle exec rake environment resque:work QUEUE=*")
end
after_fork do |server, worker|
ActiveRecord::Base.establish_connection
end
It certainly is possible - take a read of http://bugsplat.info/2011-11-27-concurrency-on-heroku-cedar.html. I've not tried it myself though but I will be soon. Essentially, you'll end up with a unicorn.rb that looks like
worker_processes 3
timeout 30
#resque_pid = nil
before_fork do |server, worker|
#resque_pid ||= spawn("bundle exec rake " + \
"resque:work QUEUES=scrape,geocode,distance,mailer")
end
I'm not entirely sure of the 'appropriateness' since it means Heroku is essentially loosing out on revenue but they haven't taken any stops to block this behaviour (nor I think would they).

Monitoring bundle exec unicorn_rails with bluepill

Due to unicorn_rails complaining about different gem versions we moved to running bundle exec unicorn_rails... in our bluepill files. This change solved that particular problem and things start and stop but when we try sudo bluepill status we now get
unicorn(pix: XXXXXX): unmonitored
Which looks like bluepill is not monitoring the unicorn processes now. It will restart the child processes if I stop them but won't restart the parent process.
I've searched around but can't find much about this issue and was hoping someone could shed some light on it. The bluepill config file is
app_dir = "/opt/local/share/httpd/apps/xyz"
Bluepill.application('xyz', :log_file => "#{app_dir}/current/log/bluepill.log") do |app|
app.process('unicorn') do |process|
process.pid_file = "#{app_dir}/shared/pids/unicorn.pid"
process.working_dir = "#{app_dir}/current"
process.stdout = process.stderr = "#{app_dir}/shared/log/unicorn.err.log"
process.start_command = "bundle exec unicorn_rails -D -c #{app_dir}/current/config/environments/production/unicorn.rb -E production"
process.stop_command = "kill -QUIT {{PID}}"
process.restart_command = "kill -USR2 {{PID}}"
process.start_grace_time = 8.seconds
process.stop_grace_time = 5.seconds
process.restart_grace_time = 13.seconds
process.monitor_children do |child_process|
child_process.stop_command = "kill -QUIT {{PID}}"
child_process.checks :mem_usage, :every => 10.seconds, :below => 200.megabytes, :times => [3,5]
child_process.checks :cpu_usage, :every => 10.seconds, :below => 50, :times => [3,5]
end
end
end
When you run bundle exec, it sets up an environment and forks the unicorn_rails process. Bluepill ends up monitoring the original bundle exec process instead of unicorn which is why you see unmonitored.
I set up my bundler environment directly in bluepill and then execute unicorn_rails directly:
Bluepill.application('xyz') do |app|
app.environment = `env -i BUNDLE_GEMFILE=#{app_dir}/Gemfile bundle exec env`.lines.inject({}) do |env_hash,l|
kv = l.chomp.split('=',2)
env_hash[kv[0] = kv[1]
env_hash
end
app.process('unicorn') do |process|
process.start_command = "unicorn_rails -D -c #{app_dir}/current/config/environments/production/unicorn.rb -E production"
end
end
(Note: I omitted part of the above config file for clarity. Your config file looks good, just try adding the app.environment stuff above and removing bundle exec from your start command.)
This sets up the environment in bluepill by capturing the bundler environment variables using backticks, parsing the returned string into a hash and assigning it to app.environment.
I know this question is old, but I've been facing this problem for weeks. My suspicions were aroused when I realised that 'bluepill quit', followed by reloading the pill while unicorn was running allowed bluepill to consider the process 'up'.
#blt04's answer didn't help. Today I came to a realization. My grace start time of 8 seconds was not enough, because I had preload_app true in my unicorn config... and my app (Rails) takes 12 seconds to load, not 8.
Raising the start time to 30 seconds (wildly in excess of what was needed) solved the problem. Bluepill just says 'starting' for 30 seconds, then goes to 'up' correctly. Unicorn starts and runs as normal.
You'll want your restart time to be longer than it takes for Rails to start too.

Rails help creating a delayed_job from a rake file

How do I create a delayed job from a rake file. How should I move it into a controller and create a delayed_job that runs the task every 15 minutes.
Here is an example how my rake file:
namespace :reklamer do
task :runall => [:iqmedier, :euroads, :mikkelsen] do
# This will run after all those tasks have run
end
task :iqmedier => :environment do
require 'Mechanize'
agent = WWW::Mechanize.new
agent.get("http://www.iqmedier.dk")
end
task :euroads => :environment do
require 'Mechanize'
require 'pp'
agent = Mechanize.new { |agent|
end
task :mikkelsen => :environment do
require 'Mechanize'
agent = Mechanize.new
agent.get("http://affilate.mikkelsenmedia.dk/partnersystem/mylogins.php")
end
end
What should I change to be a delayed job (https://github.com/collectiveidea/delayed_job)?
Suggest you take a look at SimpleWorker, a cloud-based background processing / worker queue for Ruby apps. It's designed for offloading tasks, running scheduled jobs, and scaling out to handle many parallel jobs at once. It's simple, affordable, and scalable.
(Disclosure, I work for the company.)
You create your workers (in app/worker) and then in your controllers and elsewhere queue them up to run right away or schedule them for later or on a recurring basis with just a few lines of code. Here's a basic example.
worker = ReportWorker.new
worker.user_id = #current_user.id
worker.schedule(:start_at => 1.hours.since, :run_every => 900)
#Or to run once right away
#worker.queue
The ReportWorker class would contain the logic to create the report for the current user and sent it or post it needed.
DelayedJob alone will not help you since it is based around one-time jobs. You will still need something that runs on a regular basis that creates these jobs.
Assuming:
you're on Heroku and can only get a 1-hour cron
you need to run a job every 15 minutes
You can do something like this...
Make a class for your jobs:
class MechanizeJob < Struct.new(:url)
def perform
agent = Mechanize.new
agent.get(url)
end
end
Schedule the jobs from your Rakefile:
task :schedulejobs => :environment do
urls = ["http://...", "http://...", "http://..."]
urls.each do |url|
# 1 is the job priority
Delayed::Job.enqueue MechanizeJob.new(url), 1, Time.now
Delayed::Job.enqueue MechanizeJob.new(url), 1, 15.minutes.from_now
Delayed::Job.enqueue MechanizeJob.new(url), 1, 30.minutes.from_now
Delayed::Job.enqueue MechanizeJob.new(url), 1, 45.minutes.from_now
end
end
This will run a job per url every 15 minutes.

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