Multi-user processes in Mac OS X 10.6

July 22, 2010 3:14 PM

Anybody know offhand what the default behavior of running processes in multi-user environments under Mac OS X 10.6.x might be? I suspect that logging in under the other account will suspend the processes active under the first account. Am I correct?
posted by mwhybark to computers & internet (8 answers total)

That's what it does on my machine.
posted by dolface at 3:18 PM on July 22, 2010

I can't imagine that's true. It's not much of a multi-user environment if multiple users can't use it at the same time.
posted by kmz at 3:18 PM on July 22, 2010

No, processes in the other account will still run. They may get a lesser priority, or not have access to various bits of hardware (the mouse, keyboard, screen, and maybe some audio especially), but they can still compute and use the network.

OS X is still UNIX, which was designed under the assumption that multiple users would be using the same machine all at the same time -- even though it's a less common scenario than it used to be, when 10 people were sharing a minicomputer, it still works the same way.
posted by xil at 3:22 PM on July 22, 2010

So I should conduct an experiment to see how stepped on the jobs might get. Sounds good.
posted by mwhybark at 3:39 PM on July 22, 2010

I think the one exception is iTunes -- only one copy playing at a time IIRC.
posted by Celsius1414 at 3:52 PM on July 22, 2010

You can run the command 'ps -u [user name]' in the terminal to see what processes are still running. On mine (10.5), selecting Log Out ctmf from the apple menu kills all my apps (I get a dialog box warning me about that.) If I use "fast user switching" to select another user or Login Window, and then log in again, I can see that my processes are still running.

I just tried it with 'ping' running in a terminal window, and it's still running when I come back.
posted by ctmf at 3:56 PM on July 22, 2010

If you have ssh enabled you can also ssh into your mac as a different user and run tasks. I haven't noticed my processes being put at a lower priority (I've been testing pseudo distributed hadoop on my laptop using using a separate "hadoop" user). I have not tried this with process that have a GUI (like with fast user switching).
posted by cftarnas at 4:00 PM on July 22, 2010

Test conducted, and it appears that there may be a slight performance -gain-, probably as the process does not need to manage GUI activities while running in the hidden user space. Thanks for your help.
posted by mwhybark at 5:00 PM on July 22, 2010