how can I set a scheduled task that run every second on Joomla website?
I saw different extensions but they make only every minute, like minimum threshold.
Any idea?
If you do this with a plain extension you need enough traffic to trigger the task every second. Even then this would be unreliable. The best way to do this is using a CRON job directly on your web server. This CRON job can call a CLI script or a URL on your server.
https://en.wikipedia.org/wiki/Cron
Here are some useful pages to generate the necessary task entry:
https://crontab.guru/
http://crontab-generator.org/
If you want to run it every second you might want to check this:
Running a cron every 30 seconds
There are funny solution like using sleep to increase the cron time resolution. In addition there is a tiny script in one of the answers which might help as well.
Using a Joomla extension is not reliable at all, since someone must visit the actual website for the (fake) cron to run. So, this whole cron thing when it's a Joomla extension really depends on the traffic of your website, which makes it very unreliable especially if you are developing a mission critical functionality.
Your best option is to use a Linux cron, which cannot run every second, as the minimum for a cron to run is every minute. Any solution requiring the use of sleep or a for loop is not reliable - especially when you take into consideration that you want to run something every second. All the solutions on the Internet for running a cron every second (or less than a minute) are half baked and completely unreliable. In short, you cannot run a cron every second reliably.
An imaginary solution is to have 60 servers, each server is behind the other by 1 second, and then you run the cron from each of these servers every minute. It is important that all these servers are on the same network to prevent any lag.
Related
I need to notify users of incoming end time of created data. Let's say need to notify the users after 3hrs of created data. But I dont want to run cron job every hour because this will slow down the system.
You can queue a command then add a delay to it.
use Illuminate\Support\Facades\Artisan;
Artisan::queue('your:command')->delay(60 * 60 * 3);
I haven't tried to delay a queue for hours. That's why I think a scheduled task is more reliable as you know the time when it runs.
Laravel has a Task Scheduler pretty efficient to work with cron.
You only have to configure it once to run once a minute and Laravel does the rest for checking when it needs to run.
The syntax is pretty simple and you find all available configurations on your codebase.
https://laravel.com/docs/9.x/scheduling
This hardly slows down the system since Laravel only runs the necessary.
This is pretty simple to ask, but harder to solve. The heroku scheduler addon allows for a frequency of every 10 min. But how can I retrieve data from an API every, say, 30 seconds?
I've looked into
Whether the heroku scheduler can be tricked into doing it more frequently
Can't see a way
Whether I can schedule so many of the same task that at least one is bound to run every 30 seconds
This is incredibly unproductive and imprecise, but it's the leading candidate for what I need to do
App layer libraries, like ruby's whenever gem, which won't work on heroku because of some issues with cron/persistence of dynos
Running an infinite loop at app startup - this works, but typically crashes after about 4-8 hours, and I don't know how to get it to start up again without me doing so manually.
Question
How can I reliably run a task every 30 seconds on heroku?
A side note:
I need something that works in multiple languages, for example, both rails and node at the least
You might want to try the clockwork gem.
I've been using it on Heroku for a while now and it can run a task every 30 seconds (even less). The only downside of the gem is that you need to have a specific Dyno that runs the scheduler on your application.
You could use arask. It works in Heroku and is simple to setup.
arask.create task: 'my:awesome_task', interval: 30.seconds
Hello fellow programmers. I google it before posting! Still confused about .
So here is the idea.
Users are planning post to be posted on their social media (concrete time ).
They can change post time even 2 minutes before . Cron would work as expected if it run every minute ,but it seems old solution. On the other hand queue works different (as far as I get) , trying to make better performance which means if there are high number of requests it will not post !!
Is there anything I am missing???
Thanks in advance
I personally prefere old and reliable concepts over new and unreliable one.
About cron - I did set it to run regularry user script (under the user account) and then user can modify that script how often he wants and cron runs it regularry without need for reloading configuration. And the user script can do anything user can - so it can check if time is larger than some value and some unsent messages are pending and eventually send everything needed. So even if it fails send on scheduled time (maybe server down or anything else), it would be send next time the cron hits (maybe every minute)
Is it possible to create a script that is always running on my VPS server? And what need i to do to run it the hole time? (I haven't yet a VPS server, but if this is possible i wants to buy one!
Yes you can, there are many methods to get your expected result.
Supervisord
Supervisord is a process control system that keeps any process running. It automatically start or restart your process whenever necessary.
When to use it: Use it when you need a process that run continuously, eg.:
A queue worker that reads a database continuously waiting for a job to run.
A node application that acts like a daemon
Cron
Cron allow you running processes regularly, in time intervals. You can for example run a process every 1 minute, or every 30 minutes, or any time interval you need.
When to use it: Use it when your process is not long running, it do a task and end, and you do not need it beign restarted automatically like on Supervisord, eg.:
A task that collects logs everyday and send it on a gzip by email
A backup routine.
Whatever you choose, there are many tutorials on the internet on how configuring both, so I'll not go into this details.
I'm building a monitoring service similar to pingdom but monitoring different aspects of a system and using sidekiq to queue the tasks which is working well. What I need to do is to schedule sending out pings every minute, rather than using a cron based system which would require spinning up a new ruby instance every minute I have gone down the route of using sidetiq (notice the different spelling with a "t") which uses sidekiq's own queue to schedule future tasks. This feels like a neat solution, however I am concerned this may not be the most reliable way of scheduling tasks? If there are issues with the system (as there inevitable will be at some point) will this method of scheduling tasks be less reliable than using a cron based method and why?
Thanks
You are giving too short description of your system needs but I'll try to guess how it could be:
In the first place using sidekiq means that you'll also need an instance of redis and also means that you'll need a way to monitor the sidekiq process and restart it in case of failure and possibly redis server.
A method based on cron tasks will have fewer requirements therefore much less possibilities of failing.
cron has been around for a long time and it's battle tested and it's very very reliable, but has it's drawbacks too.
Said that, you can build a system with separate instances of redis in a master/slave configuration and you can also use Redis sentinel to implement a failover in case of the master failure, implement a monitoring/alerting system on this setup (you can use something super simple like this http://contribsys.com/inspeqtor/ from the sidekiq author) and you can also start several instances of sidekiq in different machines.
With all of that, you can have a quite reliable system for running sidekiq with sidetiq.
Hope it helps