RE: Scheduling of tasks/what's the maximum frequency of the taskbeing executed?

From: Sebastijan Petrovic (SebastijanP_at_digitaldanka.com)
Date: 05/13/04

  • Next message: Daniel H. Vickers: "RE: Problem with inbound connections" 
    Date: Thu, 13 May 2004 10:42:18 -0400
To: "General Red Hat Linux discussion list" <redhat-list@redhat.com>

    Ed,

    I completely agree, however this is what has to be done;

    1. WGET is used to pull an image that changes every two seconds from an
    HTTP server, I find WGET the best tool to do this, I cannot think of a
    similar tool on a Windows side (synching does not work as well)
    2. That same image needs to be FTP-ed to a different server as often as
    it changes (2 seconds), true, SMB would be a way to go but SMB is shut
    on that server.
    3. That image would then be accessed via HTTP on that server
    (basically, HTTP in the last step is an internet resource, HTTP in the
    first step is an internal resource)

    Facts:

    1. Cannot open firewall (for various reasons-beyond my control)
    2. FTP is the only access to access HTTP server (step three) and it's
    ours
    3. Rude and resource waste it is, but the good thing about it is it's
    only needed for 2 hours and never again.

    As far as PERL scripting goes, I cannot do it to save my life, (true, I
    never attempted to), and I need this in the next couple of hours. So if
    you can spare that PERL script I'd appreciate it very much.

    Sebastijan
    -----Original Message-----
    From: redhat-list-bounces@redhat.com
    [mailto:redhat-list-bounces@redhat.com] On Behalf Of Ed Wilts
    Sent: Thursday, May 13, 2004 10:22 AM
    To: General Red Hat Linux discussion list
    Subject: Re: Scheduling of tasks/what's the maximum frequency of the
    taskbeing executed?

    On Thu, May 13, 2004 at 09:23:48AM -0400, Sebastijan Petrovic wrote:
    > I have several tasks that need to be executed every two seconds.
    Using
    > RH9 builtin task scheduler the greatest frequency of a task is every 5
    > minutes. At command also does not allow for such frequent schedule.
    >
    >
    >
    > Do any of you know of a way to accomplish this. Details of what I
    need
    > done are as follows:
    >
    > 1. Run WGET to download an image (that changes every two seconds)
    > using http, keep over-writing that image and
    > 2. Upload that image every two seconds to an FTP share

    Against my better judgement, since I have some doubts that you really
    want to do this, here's how I would tackle this:

    1. Do not use any scheduler whatsoever.
    2. I'm assuming the FTP server is yours. Trying to log into somebody
    else's FTP server every 2 seconds goes beyond rude - it's offensive.
    3. Write a perl script to do the get & put. Don't use wget but use the
    callable routines to get the file. Open a single FTP session and put
    the file regularly. Better yet would be to write a custom app to copy
    the file over, or even better would be to not copy the file over unless
    it's needed - either via nfs, smb, or something. Copying the same image
    every 2 seconds is a large waste of resources unless users are actually
    pulling that image off your FTP server every 2 seconds.
    4. Do *NOT* try to log into the FTP server every 2 seconds to put a
    file. FTP isn't that efficient and doing a new login every 2 seconds is
    going to kill the FTP server. 

    -- 
Ed Wilts, Mounds View, MN, USA
mailto:ewilts@ewilts.org
Member #1, Red Hat Community Ambassador Program
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  • Next message: Daniel H. Vickers: "RE: Problem with inbound connections"

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