[Swift-user] Set maxtime > maxwalltime or your script will hang

[Mihael Hategan]

On Tue, 2010-04-27 at 06:04 -0500, wilde at mcs.anl.gov wrote:
> [cc'ing swift-user]
> 
> Marcin, 
> 
> Quick answer: Since you changed the maxwalltime in tc.data to 10
> minutes, change the "maxtime" setting in sites.xml to N times 10
> minutes *plus* 1 minute. The "plus" is important.
> 
> Long answer:
> 
> Swift deducts a small fraction of maxtime to use to cleanly shut down
> the PBS job. The default for this "reserve time" (see the Users Guide)
> is 10 seconds. So while before it was happily fitting 15-second jobs
> (the prior setting you had for maxwalltime) into (600-10) second
> slots, now (with maxwalltime increased to 10 minutes) it could not
> find any slots into which it could fit a 10 *minute* job.
> Unfortunately, at the moment, Swift just hangs, continuing to try to
> find a slot until the maxtime time runs out and the PBS jobs shut
> down. (There are "good" reasons for this "bad" behavior, which we need
> to fix)

A comment there:
Set the "maxtime" coaster parameter if you know that the queue you are
using has a limit to the time a job can have. Don't set it because your
jobs have a certain maxwalltime. It's purpose is to prevent the creation
of blocks that cannot be run on a given queue.