As of r3197 there's been a timeout on calls to change_power_action() in provisioningserver.rpc.power. This is hard-coded to two minutes, after conversation with Dustin on IRC:
11:29 < gmb> rvba, jhobbs, kirkland: Realise you're in Brussels but… I'm looking to add a timeout to the code that runs power actions on nodes (as part of fixing https://bugs.launchpad.net/maas/+bug/1376782). Obviously this involves some guesswork (I don't know how long these things take to run on, say, IPMI nodes). Is 60 seconds too short? What about 5 minutes?
11:29 < gmb> allenap: Also would like your opinion on ^^
11:30 < kirkland> gmb: 2-5 minutes, I'd think, gmb
11:30 < kirkland> gmb: maybe expose it as a config option for the admin to twiddle?
11:30 < kirkland> gmb: with a sane default of 2m?
11:31 < gmb> kirkland: That'd be nice; for 1.7 I'll go with a sane default and maybe we can make it configurable in 1.7.1 (too many nasty bugs to fix to start adding new UI elements).
11:31 < kirkland> gmb: ack
11:31 < gmb> kirkland: Thanks for the advice.
11:32 < kirkland> gmb: let's set to 2m for 1.7, and make it configurable by the admin for another releas
I think we should avoid having more knobs to twiddle. Apart from anything else it's another question to ask when a user needs help with power control: "What have you got the global power time-out set to? Oh, that's a bit low/high, try X...".
However, it may be useful to allow the power drivers to declare an overall time-out value. The AMT driver might want 5 minutes, whereas virsh might be happy with 1 minute.