# Timer Task? **URL:** \ **Category:** Ruby\ **Created:** [September 9, 2006, 4:28pm UTC](https://www.ruby-forum.com/t/timer-task/68130 "2006-09-09T16:28:27Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![vinsonizer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@vinsonizer](https://www.ruby-forum.com/u/vinsonizer)\ **Post date:** [September 9, 2006, 4:28pm UTC](https://www.ruby-forum.com/t/timer-task/68130/1 "2006-09-09T16:28:27Z")
Disclaimer: I’m relatively new to Ruby, but I love it. 🙂 I’m writing my first real ruby utility on my own (using the snarl library [http://www.fullphat.net/](http://www.fullphat.net/) plus [Google Code Archive - Long-term storage for Google Code Project Hosting.](http://code.google.com/p/ruby-snarl/) and net/imap for new mail notification), and it’s working fine, other than the fact that I don’t know how to schedule a recurring job. I’m looking for something similar to the Timer class in java for scheduling jobs in ruby. Is there such a thing in the core api? Thanks in advance, Jason ---
**Author:** ![vinsonizer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@vinsonizer](https://www.ruby-forum.com/u/vinsonizer)\ **Post date:** [September 9, 2006, 6:08pm UTC](https://www.ruby-forum.com/t/timer-task/68130/2 "2006-09-09T18:08:35Z")
> I’m writing my first real ruby utility on my own (using the snarl library > [http://www.fullphat.net/](http://www.fullphat.net/) plus [Google Code Archive - Long-term storage for Google Code Project Hosting.](http://code.google.com/p/ruby-snarl/) and > net/imap for new mail notification), and it’s working fine, other than the > fact that I don’t know how to schedule a recurring job. I’m looking for > something similar to the Timer class in java for scheduling jobs in ruby. > Is there such a thing in the core api? This doesn’t answer your question, but, is your utility actually a full-fledged client? Or just what someone would use to send off emails/notifications once per session. My point is, does this utility run constantly? Or just once when needed? If you leave it running constantly, I think you already have a main loop going on, so why not have a little method to handle scheduled/recurring events at whatever interval you do have? Maybe if you could clarify a little better… I must admit, though, that this is far from my expertise, and perhaps someone with a little more experience with this kind of thing would be able to help you far better! (But I’m trying!) M.T. ---
**Author:** ![vinsonizer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@vinsonizer](https://www.ruby-forum.com/u/vinsonizer)\ **Post date:** [September 9, 2006, 7:26pm UTC](https://www.ruby-forum.com/t/timer-task/68130/3 "2006-09-09T19:26:43Z")
Jason Vinson wrote: /… > Does sleep cost anything in terms of resources, and if so what is > “cheaper”? AFAIK “sleep” is a perfectly adequate way to idle a thread, and it has the advantage of being trivial to implement. I have recently seen Ruby threads that used “sleep” be idled by the thread manager, never to be called again, but this has to do with Ruby threads within a Ruby process, not native threads represented by particular Ruby applications. [Somewhat OT] Have you considered using OS-specific facilities like “cron” instead of “sleep” for scheduling? I use cron for most of these periodic, relatively low-powered tasks because it is easy to add a task to cron’s list of jobs, and it burdens the system less than maintaining a bunch of sleeping processes – cron loads, runs, and unloads its tasks, while a sleeping process represents an ongoing use of resources. ---
**Author:** ![vinsonizer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@vinsonizer](https://www.ruby-forum.com/u/vinsonizer)\ **Post date:** [September 9, 2006, 6:22pm UTC](https://www.ruby-forum.com/t/timer-task/68130/4 "2006-09-09T18:22:36Z")
Hi Matt, Thanks for the reply. I am trying to schedule a recurring task, so it would run constantly. I guess my real question is the preferred approach something like this? notifier = SnarlMail.new(“[imap.mailserver.com](http://imap.mailserver.com)”, “username”, “passwd”) while(true) do notifier.check sleep 60 end Does sleep cost anything in terms of resources, and if so what is “cheaper”? Thanks, Jason ---
**Author:** ![vinsonizer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@vinsonizer](https://www.ruby-forum.com/u/vinsonizer)\ **Post date:** [September 9, 2006, 9:23pm UTC](https://www.ruby-forum.com/t/timer-task/68130/5 "2006-09-09T21:23:00Z")
-----Original Message----- From: Paul L. [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] Sent: Saturday, September 09, 2006 1:20 PM To: ruby-talk ML Subject: Re: Timer Task? Jason Vinson wrote: /… > Does sleep cost anything in terms of resources, and if so what is > “cheaper”? AFAIK “sleep” is a perfectly adequate way to idle a thread, and it has the advantage of being trivial to implement. I have recently seen Ruby threads that used “sleep” be idled by the thread manager, never to be called again, but this has to do with Ruby threads within a Ruby process, not native threads represented by particular Ruby applications. [Somewhat OT] Have you considered using OS-specific facilities like “cron” instead of “sleep” for scheduling? I use cron for most of these periodic, relatively low-powered tasks because it is easy to add a task to cron’s list of jobs, and it burdens the system less than maintaining a bunch of sleeping processes – cron loads, runs, and unloads its tasks, while a sleeping process represents an ongoing use of resources. – Paul L. > **[\* arachnoid.com](https://arachnoid.com/)** > > A site for people who think. Intellectual resources, programming, astronomy, science, mathematics, Java/JavaScript applets, programming instruction, home of Arachnophilia. … Thanks for the reply Paul, The main reason for maintaining a Thread is because there’s a tiny bit of state involved (I only want to report new mail, not the same new mail over and over again). I’m open to other alternatives, but writing out to the file system seems like the only other option, which I’d prefer not to do. Jason ---
**Author:** ![vinsonizer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@vinsonizer](https://www.ruby-forum.com/u/vinsonizer)\ **Post date:** [September 9, 2006, 9:45pm UTC](https://www.ruby-forum.com/t/timer-task/68130/6 "2006-09-09T21:45:08Z")
Jason Vinson wrote: > [Somewhat OT] > > Have you considered using OS-specific facilities like “cron” instead of > “sleep” for scheduling? I use cron for most of these periodic, relatively > low-powered tasks because it is easy to add a task to cron’s list of jobs, > and it burdens the system less than maintaining a bunch of sleeping > processes – cron loads, runs, and unloads its tasks, while a sleeping > process represents an ongoing use of resources. Amen to that! Anything that is done once a minute or less frequently should be done with “cron” or the Windows equivalent, whose name I’ve forgotten. However, if you need to do something more often than once a minute, in most cases “sleep” is a perfectly acceptable way to do it. One caution: most languages and operating systems can’t guarantee that the actual time elapsed between the call to “sleep 10” and the next operation will be anything even close to 10 seconds. Usually, the guarantee is that it will be _at least_ 10 seconds. 🙂 If you actually need precise timing, you’ll need to dig into the OS, system calls, priorities, schedulers, etc. ---
**Author:** ![vinsonizer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@vinsonizer](https://www.ruby-forum.com/u/vinsonizer)\ **Post date:** [September 9, 2006, 10:13pm UTC](https://www.ruby-forum.com/t/timer-task/68130/7 "2006-09-09T22:13:13Z")
Jason Vinson wrote: > The main reason for maintaining a Thread is because there’s a tiny bit of > state involved (I only want to report new mail, not the same new mail over > and over again). Â I’m open to other alternatives, but writing out to the > file system seems like the only other option, which I’d prefer not to do. First, there’s something misconfigured about your newsreader. Look at my earlier post, and your reply (to which I am replying). You will see that my text isn’t “quoted” in your reply, but it appears as though it is the new content. Second, writing to a file in /tmp could be a reasonable way to get the state you need. You could purge the file on each reboot. Nevertheless, I see your point about statefulness. Another way to do this is to have state information in the user’s home directory (I meant to suggest the user-level cron facility, not the root cron), under the name of the application, that can be updated without requiring systemwide resources. It’s a tradeoff worth thinking about, because a continuous, sleeping Ruby app requires a Ruby interpreter to provide for it, whereas a Ruby app executed by cron only requires transient resources. ---
**Author:** ![vinsonizer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@vinsonizer](https://www.ruby-forum.com/u/vinsonizer)\ **Post date:** [September 10, 2006, 1:21am UTC](https://www.ruby-forum.com/t/timer-task/68130/8 "2006-09-10T01:21:41Z")
> The main reason for maintaining a Thread is because there’s a tiny bit of > state involved (I only want to report new mail, not the same new mail over > and over again). I’m open to other alternatives, but writing out to the > file system seems like the only other option, which I’d prefer not to do. I think not using this fantastic resource available to us is a bit silly. That’s the whole reason the filesystem exists: persistent storage! So, store the state and the emails, or just the state if you prefer. Whichever. But I think it’s a bit silly not to use the filesystem. Also, I’m definitely in favor of cronning something like this as well. 😃 M.T.