I've been doing Seti@Home for over a decade but haven't dug into the details too much of BOINC, just let it run.

I did play around and set BOINC up to run three projects = SETI, Milkyway and Rosetta with a resource share as 80%, 10% and 10%, respectively.

However, I'm finding that the Rosetta project downloads, all at once, about six to eight 6-hour tasks that are all due in 10 days. A week or so after download, BOINC starts running these Rosetta files exclusively, as high priority, regardless of my 80/10/10 resource share setting.

Currently, I'm managing BOINC by aborting the extraneous Rosetta files but when BOINC reports back to Rosetta with one "Ready to Report" task and 6 aborted tasks, Rosetta then sends a whole new set of 6-hour tasks due in 10 days.

Essentially Rosetta's figured out how to co-opt computer resources at the expense of other projects with this tactic, ignoring the computer user's wishes.

Is there a way to prevent Rosetta from downloading so many tasks?

At Rosetta's project preferences you can tell how long the tasks should run, at maximum (Target CPU run time). Perhaps you may want to change it to an hour, or so.

Apropos,

A week or so after download, BOINC starts running these Rosetta files exclusively, as high priority, regardless of my 80/10/10 resource share setting.

Not despite, but because of your 80/10/10 setting, as what else did you expect would happen when a project has a 10 RS, a lot of work, and a (reasonably) short deadline? BOINC will always try to finish all work in cache before their deadline.

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