hwmond high cpu load after 10.6.8 update

Yes, I'm having the same exact problem. I have an '08 Xserve, dual-proc, quad-core, and it's taking up 95%, effectively one entire core.

Since the 10.6.8 update it won't restart successfully either, I've had to restart it either via command line or the Apple Menu, then go over and hold the power button down to forcefully shut it off. I have not tried doing the final step via LOM yet.

Edit: And just to drive the point home I tried restarting it (via methods mentioned above) and then let it sit for 4 hours unattended, it never restarted.

Message was edited by: InfraredAD

10.6.8 yikes

Same here on Xserve1,1. Bug reported.

If you haven't reported the bug directly to Apple, please do so on http://bugreport.apple.com/.

I'm experiencing this problem with my Xserve as well, and I've filed a bug report.

Didn't see anyone mention this, but you can stop hwmond from using all that CPU time by unloading it with launchctl:

sudo launchctl unload /System/Library/LaunchDaemons/com.apple.hwmond.plist

That will stop it until the next time your Xserve boots.

In my case:

1. I installed 10.6.8 via the Combo Update, was running 10.6.7 previous to this.
2. /System/Library/LaunchDaemons/com.apple.hwmond.plist still exists and is not empty
3. /etc/hwmond.SMART still exists and is not empty
4. /etc/hwmond.conf didn't exist, so from Terminal.app I simply issued "sudo touch /etc/hwmond.conf"

I tried:

1. In Terminal.app, ran:

   sudo launchctl unload /System/Library/LaunchDaemons/com.apple.hwmond.plist

2. Then, backed up /usr/sbin/hwmond and /System/Library/LaunchDaemons/com.apple.hwmond.plist
3. From a Mac Pro running 10.6.7 Server, copied both the binary and the plist to the same spots on the Xserve, then, in Terminal.app, ran:

   sudo launchctl load /System/Library/LaunchDaemons/com.apple.hwmond.plist

4. That didn't change a thing. hwmond still spiked.
5. Put everything back the way it was.

And:

1. In Terminal.app, ran:

   sudo launchctl unload /System/Library/LaunchDaemons/com.apple.hwmond.plist

2. Backed up /System/Library/LaunchDaemons/com.apple.hwmond.plist
3. Made another copy to the Desktop
4. Edited this copy and added a string in ProgramArguments with a value of "-S255", but this still caused hwmond to spike after putting this copy back in LaunchDaemons, repairing permissions, and loading the plist via launchctl again.

   Any valid value still caused it to spike. However my Xserve now reboots if I set the value to an invalid value, like "-s256". Then again this also caused com.apple.hwmond and com.apple.launchd to create entries in the system log complaining about the value with hwmond attempting to relaunch itself every 10 seconds:

6/24/11 2:37:10 PM com.apple.hwmond[2697] hwmond: n should be 1 to 255 seconds

6/24/11 2:37:10 PM com.apple.launchd[1] (com.apple.hwmond[2697]) Exited with exit code: 1

6/24/11 2:37:10 PM com.apple.launchd[1] (com.apple.hwmond) Throttling respawn: Will start in 10 seconds

OP, Armin, did something similar, but I think he tried doing it directly in Terminal, not using launchctl / launchd, which caused the error he mentioned.

1. Finally, added a "Disabled" item, with a boolean value of YES to the plist, recopied it, repaired permissions again (launchctl will complain and won't load the plist if you don't). This way hwmond is disabled, I can reboot my Xserve, and wait until Apple figures this out.
2. Full com.apple.hwmond.plist on my Xserve looks like this now:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">

<plist version="1.0">

<dict>

<key>Label</key>

<string>com.apple.hwmond</string>

<key>OnDemand</key>

<false/>

<key>Program</key>

<string>/usr/sbin/hwmond</string>

<key>ProgramArguments</key>

<array>

<string>hwmond</string>

<string>-s255</string>

</array>

<key>ServiceIPC</key>

<false/>

<key>Disabled</key>

<true/>

</dict>

</plist>

Edit: I too have filed a bug report with a link to this thread included.

Second Edit: Server Monitor.app still works after disabling hwmond via the plist even after a reboot.

Third Edit: Sorry, keep remembering things, a modified /usr/sbin/hwmond was included the 10.6.8 Server Combo Update package, but not the Delta. Not sure if this matters. How has everyone updated to 10.6.8 so far? Like I mentioned, I used the Combo.

The downside to disabling hwmond is it's not available to periodically report on the hardware, nor does it provide feedback to the front fascia LEDs on the Xserve (not including the ADM ones). LEDs I can live without, reporting, not so much. I'll probably end up rebuilding in a few days if there's no official fix for this. And I'll use the delta updater provided through ASU.

Yep. Same here.

I too installed the combo update.

Dös this problem only occur when installing the combo?

I installed from Software Update and I have the problem.

+1

combo update

Were you running 10.6.7 Server prior to running the update?

Hate to spoil the assuption its the combo update........but I was running 10.6.7 and ran software update on my two servers and installed 10.6.8. So I most likely installed the delta update.

Having the same issue with the process and filed a bug report as well. Hopefully they get this fixed quickly!

All fixed for me.

just use Time Machine, I was back to 10.6.7 in 2 minutes.

Same problem here.....