I have been looking for a time based persistent scheduler. I looked into some applications (Agenda, node-cron, node-schedule). But I couldn't find anything that satisfies my criteria.
So my applications sends out reminders to our customers based on their event timings. I am hesitating to run a regular cronjob because I have to run every 15 mins or so in this case. And for each cronjob, I have to make a database call. I am trying not to use resources unnecessarily.
In addition to that, I am already running a lot of cronjobs. But in my case, when the job is completed, I want the cron to get cancelled/finished; not live on memory until the server restart happens.
I tried using the above specified applications by setting exact timestamps (agenda, node-cron, node-schedule). But the cron lives on forever even after the job is completed, and if i restart the server, all the scheduled jobs are cron. So persistence is also an issue I am facing.
My server uses node js. If there are any other languages/tools to make this work, I am all ears.
Looking forward to your help.
I tried following this solution. But this solution is for one predefined event. In my case, the number of reminders to be sent out are dynamic and jobs are to be scheduled on the fly.
Related
I have a web application, where users can schedule different jobs.
I'am not sure how to proceed with this.
All the nodejs schedulers out there basically reads the schedule from within the code. I can of course implement this cron like schedule to be read from a database, but I'am not sure if its the most effective way?
If I back the solution with a database I would need to query that database, let say each second, to see if there is any schduled jobs that needs to be handled. I can't read them once a day, because new jobs might be added on a regular basis.
Keeping them in memory dosen't seem very efficient either?
Am I looking for a different kind of technology to handle this, than a scheduler+database?
We are talkning around 10.000 jobs for the time being (as a maximum). They are mostly related to sending emails and/or giving notifications within the application itself.
So, I see that heroku provides the option to run a command at a specific time. Information on the scheduler here.
LINK: https://elements.heroku.com/addons/scheduler
However, if you go through the steps when setting it up, they do not provide a lot of flexibility on when you can run your code daily. For example, you can only run code at 4:00pm or 4:30pm, not 4:10pm.
How can I make it so that a node.js file would run on heroku at a specific time (like 4:10pm or 2:15pm, some time outside the options given on heroku) on a daily basis?
There appears to be no support for node.js explaining this either on their website.
Might be just a work around, but you could start the process at the nearest time slot, that is before your desired time, let it run and wait passively until your desired time and let it do the actual task just then.
However notice as Heroku mentions in the documentation Heroku Scheduler isn't guaranteed to run the task, even though it's very reliable. If you need something critical or have something that has to been run everyday for sure, you should probably make a separate process, which handles the scheduling.
We've added a simple Heroku add-on called Cron To Go that does exactly that - you can use Cron expressions for accuracy and schedule one-off Dynos, just like with Heroku Scheduler.
There's also a simple Node example here.
I'm creating a project in Node & Express that allows users to schedule the server to run test scripts e.g. once every ten minutes. I looked into node-schedule which looks great however it seems that all scheduled tasks disappear if the server ever restarts Node.
Cron looks good too but it has the problem that it doesn't seem to have a way to delete scheduled tasks after they have been set up.
If you were doing this, how would you go about it? I really don't want anything that's going to be complex, just need to schedule tasks, be able to delete individual tasks, and keep tasks in the event of a server reboot.
Simplest solution is to store the configurations for Cron in a database (since it takes a string as a parameter). Load the jobs from the db every time the app starts.
I've setup a node.js server with cron jobs via node-cron, which is js-land cron implementation. I've noticed that sometimes the jobs are not launching, aparently without errors and following an unknown pattern.
Well, since this server is a free one, I was thinking that maybe it goes to sleep when there is no activity, so that the jobs are not launching. I've looked the docs and I haven't seen any clear indication on this.
I've already seen the Cron addon, but I'm not interested on it. I'll like to make it work within a js process.
Thanks!
cloudControl uses Container idling (https://www.cloudcontrol.com/dev-center/Platform%20Documentation#deploying-new-versions) for free deployments.
If a free deployment (1 container with 128MB) does not get any requests within a timeframe of one hour the container is idled ("server goes to sleep").
I've seen that Heroku charges $15/mo to run Delayed Job, and $3/mo to run cron tasks daily. Is it possible to skip that entirely and run my own cron tasks manually? Or are they somehow figuring out that I'm running cron tasks?
I'm not entirely sure what you mean by "run my own cron tasks manually". For cron specifically, you need access to crontab, which they can control, as they're their servers. If you have another way of doing it, it would probably be fine, but bear in mind that your app is not tied to a specific server when running under Heroku, and that the server will change between executions.
Also, unless they've changed it since last time I checked, you can run daily cron tasks for free, but hourly costs $3/mo.
EDIT: Yes, daily crons are free. See http://addons.heroku.com/.
If you install the Heroku gem on your computer, you can then run your cron tasks manually as follows:
$ heroku rake cron
(in /disk1/home/slugs/xxxxxx_aa515b2_6c4f/mnt)
Running cron at 2010/04/25 10:28:54...
This will execute the exact same code as Heroku's daily/hourly cron add-on does; that is, for this to work, your application must have a Rakefile with a cron task, for example:
desc "Runs cron maintenance tasks."
task :cron do
puts "Running cron at #{Time.now.strftime('%Y/%m/%d %H:%M:%S')}..."
# TODO: your cron code goes here
end
Now, just add the heroku rake cron command to a crontab on any Unix server of yours, or even directly to your personal computer's crontab if you're running Linux or Mac OS X, and you can be scheduling cron jobs for your Heroku application as you please and without being charged for it.
Updating the answer for 2020:
You can use Heroku Scheduler which is Heroku's own add-on that lets you schedule commands using one-off dynos (so that you only pay for the run time of your jobs). The add-on itself is free, but doesn't really allow you to use cron but rather plain frequency: every day, every hour or every 10 minutes. Also, there's no guarantee that your job will execute at the scheduled time or at all..
There are other 3rd party add-ons that can help you run one-off dynos using cron expressions for better flexibility and are more resilient than Heroku Scheduler (proper disclosure, my company is the creator of one such add-on).
You can also use custom clock process (see here for more info) which essentially means that you have one dyno or process spawn tasks that run on other dynos. This usually costs more than using the aforementioned add-ons, but you have more granular control over your processes and since you only rely on Heroku, it may be more stable.
Yes, I've successfully used a cron job on my local server which essentially runs
$ heroku rake <rake task>
at whatever intervals I've required. I've used in on both aspen and bamboo stacks.
You can also just install a gem like rufus-scheduler if you're running a rails app and setup scheduling that way. I don't know if this is bad practice for some reason, but it's what I do with my app, and it seems to work fine.
If you want to have scheduled jobs you can also use http://guardiano.getpeople.in that is a free service (for 10 jobs) for job scheduling.
You just need to setup an HTTP endpoint in your application to recieve event notifications on POST or GET and you can also set some additional params to prevent not authorized actions.
So you set a job in Guardiano that will cal http://yourapp.com/youraction and leave "minutes" blank if you want you action to run once in the future or set minutes to what you want to run your action every X minutes. In that way you only have to create your endpoint for you app and when this EP is called you execute something.
So your app can sleep and you don't need to spend money and time setting up jobs and taking care that they are working properly.
IMHO if you need something fast for an MVP or you need to setup a lot of jobs for different apps than a free service like that where you can actually outsource cronjobs is quite good.
There was aslo an Heroku Addon called Temporize to do that but I'm not sure is still alive and working