Phantom Tasks


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Questions and Answers : Macintosh : Phantom Tasks

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Big Bang
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Message 1040939 - Posted: 11 Oct 2010, 4:04:25 UTC

Given the recent roller coasters our keepers of the Seti matrix machine have endured in recent times I will not waffle on about the following problem but would very much appreciate some explanation as to what has occurred. I have noticed three tasks registered on site that were supposedly transmitted to me on 30 September according to the records, but there is no sign in my Boinc software of them having been downloaded. Is this due to the technical hiccups or is there a more nefarious reason that may satisfy my pinings for the plausible paranoia?
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OzzFan
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Message 1040953 - Posted: 11 Oct 2010, 4:52:14 UTC - in response to Message 1040939.

In fact, we don't know what actually causes them. It's been rather hard to pinpoint as to what actually creates them, but it's definitely server-side. "Ghost" or phantom workunits have been happening since long before the recent server issues, so it can't be blamed on that.

My educated guess is that the server creates the workunit, puts it in a queue to be downloaded, then a machine requests more work. For some reason, the server assigns the task to a machine, thinks it sends it but the process fails.

This seems to be something unique to the BOINC server software since a feature was added to specifically reduce ghosts on user's machines called "Resend". Resend checks the user's machine for all their workunits and compares it to the server's list of what it's supposed to have and if any are missing, it simply resends those workunits.

Problem is, the resend feature is very database intensive, especially for such a popular project like SETI@Home. Since SETI's database can hardly handle the normal traffic at this point, the features has been turned off. Hopefully, when they get some faster/newer hardware, they might be able to turn it on again. We'll see.

Big Bang
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Message 1040988 - Posted: 11 Oct 2010, 8:45:19 UTC - in response to Message 1040953.

Thankyou very much for your speedy and informative response $o |>0/|/3.

...I suppose it would be fruitless then to surround my residence with salt/garlic and ward off any Seti cyber-poltergeists.

Sigh.

Logical reasoning is so insanely mundane ;)

Cheers mate.
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Questions and Answers : Macintosh : Phantom Tasks

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