hwmond high cpu load after 10.6.8 update

Same problem here. Xserve Xeon, monoproc. 10.6.7 to 10.6.8 through ASU. hwmond is taking 84% on a single cpu.

Confirmed this same bug on a colleague's 2009 Xserve, however he can reboot, whereas my 2008 wouldn't without hwmond being disabled via launchctl/launchd. Taking up 85 - 94% CPU on his.

Something else I've noticed, and this is kind of out there, but the processor LEDs are very choppy after the 10.6.8 update. On 10.6.7 and older they used to increase or decrease smoothly.

Same issue. 10.6.5 to 10.6.8 via ASU. That should mean combo update. It is a xserve 3,1 and will still reboot fine. Took a reboot or 2 to get AFP working for users but now seems to work OK even with hwmond chewing up a core.

I'm seeing hwmond bounce between 86% and 93% on an Xserve2,1 dual 2.8 quad core. Reboots don't help.

No problems on our Xserve3,1 dual 2.66 quad core.

Both where updated from 10.6.7 to 10.6.8 with the delta updater.

I updated from 10.6.7 to 10.6.8 on my Xserve 3,1 with a 2.26GHz Quad-core Intel Xeon processor at about 5 AM on 6/25/11. I noticed hwmond using a steady 95% CPU on one core shortly afterwards. I found this thread later that day and have been watching it to see what others were reporting.

Oddly enough, at about 10 AM today (6/27/11), hwmond stopped hogging CPU and is now down to a normal level (.4% with a brief increase to 1.9% every few seconds). It has been following that behavior since then. Well, I suppose that's normal behavior. I'm fairly new to the Snow Leopard Server / Xserve platform, so I don't have much background to speak of.

I sure do appreciate all of the expertise that is shared here, though.

Interestingly this only affects my Xserves, my Mini servers do not have this issue. So it must be a bug in how hardware monitoring is communicating with the sensors in the xserve that is giving it fits or this is Apple's way of making us try and get rid of our xserves, haha.

Same problem, Xserve 1,1 dual dualcore 2.0ghz. I used launchctl -w to unload hwmond until such time that it is fixed. Combo update did NOT help.

Accessing a Windows Server 2008 (64-bit) with a MacBook Pro 6,2 running 10.6.8. The MBP is doggedly slow and response time is minutes but Activity Monitor shows nothing unusual. Could this be a similar problem? MBP works fine when not connected to the Windows Network.

No, hwmond is specific to Mac OS X Server as far as I know. You'd also see a hwmond in "all processes" in activity monitor consuming 70-96% CPU.

hwmond also deals specifically with Xserves; it's installed along with the rest of OS X Server, but doesn't run/work on anything but. Here:

http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/ man8/hwmond.8.html

Looking at the logs shows everything running normally right after the 10.6.8 update but after two entries the log has not been updated since Friday.

I now have the same problem on two servers.

Xserve1,1

Xserve3,1

I have opened a case at AppleCare Premium Service...

Me too.

86% on Xserve 1,1

I have the same problem. Used the Combo update on two new Xserve 3,1 and they both hover around 90% for the hwmond process.