Computers running Wolfram lightweight grid manager won't fall asleep

Question

I have a computing environment comprised of:

• 27" iMac with dual cores running Mac OS X 10.6.8 and
• 2 XServes each with 2 quad cores running Max OS X Server 10.6.8
• All networking by ethernet to a Time capsule.

I now run Mathematica on the iMac and use the XServes for parallel processing.

I have Wolfram lightweight grid manager running on the XServes.

Since installing the grid manager the XServes won't fall asleep. Their energy use settings look like this:

which should trigger them into sleep mode after 5 minutes of inactivity.

The warm summer weather has made this a pressing issue. XServes run hot and power hungry. I don't need them running constantly and don't want to run air conditioning all the time to cool them. Also, I want to run some processing from a remote location while I escape NY's summer heat for a few days. Sleeping and waking the servers figure into my working vacation plan ;-)

Does grid manager run some process which prevents the XServes falling asleep? If so, how can I start and stop the process?

Answer 1

I just got some feedback on this question from Premier Support.

1. The Wolfram Lightweight Grid Manager runs as a service. As a constantly running service (essentially always listening for a parallel processing job) it always keeps the XServes active so they don't experience the inactivity required to sleep.

2. The solution requires shutting down the service and secondarily starting the service prior to launching parallel kernels and submitting a parallel processing job.

I'll have a followup question on how to do #2 from Mathematica, because I think it has broader application than just this problem.

Answer 2

Lightweight Grid Manager is a service, implemented as a Tomcat-based web application, that is always on ready to accept requests to launch Mathematica kernels. That is its purpose.

You can refer to the official documentation for stopping and starting the service for Mac, Linux, and Windows.

If this becomes inconvenient, you could use ssh for remotely launching kernels.