X

Mac OS X 10.5.x Special Report: High fan activity, processor usage

Mac OS X 10.5.x Special Report: High fan activity, processor usage

CNET staff
4 min read

Some users are reporting abnormally high fan activity under Leopard.

First, readers are reminded that when some process cranks up and starts taking over your computer's ability to get anything done - a phenomenon often signalled, especially on a portable, by the noise of the fans whirring up, to keep those overworked logic board components cool - you can usually finger the responsible party by opening Activity Monitor (in the Utilities folder). Switch the pop-up menu to All Processes, if necessary, and then click on the CPU column header so that processes using the highest percentage of your CPU(s) come to the top. Taking 10% or 20% of the CPU is fairly normal, but if a process is using 70% or more of the CPU, and if it does this persistently, you might suspect that not all is well.

MacFixIt reader James Tarpley writes:

"I've installed 10.5 in 3 Macs (yes I purchased a 5 seat license): a quad core G5, a G5 iMac, and a G4 laptop, 24 hours after installation, all 3 are running fans at a higher than normal speed - it's constant until the Mac is placed in the sleep mode. Examination of the Activity Monitor reveals on all there 'root' activity consuming nearly 100% of the processors capacity. The root activity involves 'CrashReport' and 'mds'. I'm not knowledgeable enough to know what these activities are, but I'm quite certain it's abnormal. As one would expect, the for a couple hours after installation the drives were busy with indexing - this current activity is something else."

Interestingly, as Tarpley's report contains mention of spiking processor usage from the CrashReport process, we've also received reports indicating problems submitting crash reports to Apple, with the system being unable to find specific files (note that Tarpley also mentions "mds" -- a crucial component of Spotlight handling metadata) -- a sure cause for spiking processor usage and consequential inordinately high fan activity.

MacFixIt reader David writes:

"When an application crashes, you get the error message that it crashes and if you want to send a report to Apple. If you agree to, it searches for the System Configuration and eventually fails to find it, and so the report doesn?t get submitted to Apple. This has happened with two different applications."

The temporary fix for this issue is to use Activity Monitor to kill the CrashReport process, the mds process, and others that are spiking in processor usage. See this tutorial for more information on doing so. In some cases, simply killing a process and allowing it to restart will alleviate the issue.

Another cause: QuickLook and Transmission

As described in this blog entry and accompanying screen shot, fans may run hot because the Quick Look Server process is taking up way too much of the CPU, as shown in the first line of the screen shot. It's not hard to guess what the Quick Look Server does; it's probably the process responsible for keeping track of Quick Look "generators" on your computer. The "generators" are consulted whenever you ask to view a Quick Look preview. (See also our earlier coverage of Quick Look previews and how they come into existence.)

The clue as to why the Quick Look Server is being overworked, however, seems to lie in the second line of the screen shot: the application Transmission is also running. It appears to be Transmission itself that is prodding the Quick Look Server into excessive action. This hypothesis is also raised over on the Transmission forum.

It is not clear whether the cause is, as one user suggests, that the Quick Look Server is "trying to index the bittorrent files while they are downloading". It isn't entirely obvious what Quick Look Server would be "indexing"; is it hunting for "generators"? Or is it rather, perhaps, Transmission itself that interacts incorrectly with Quick Look? In any case, readers might want to be wary of Transmission until these issues are ironed out; whatever's going on, this behavior can't be right, and Transmission seems to be responsible for it.

By the way, researching this story, we discovered that you can easily obtain a conspectus of all "generators" that the Quick Look Server knows about, by typing the following into the Terminal:

qlmanage -m

The output tells you what generators you've got, listing, for each one, where it is installed, and what kind of document it understands (couched as a Uniform Type Identifier, or UTI). For example, Quick Look knows how to preview a font file (UTI "public.font") because of a generator built into the QuickLook framework. But it knows how to preview a Pages document (UTI "com.apple.iwork.pages.pages") because, if you have the current version of Pages, an iWork generator has been installed into /Library/QuickLook.

Resources

  • this tutorial
  • blog entry
  • earlier coverage
  • Transmission forum
  • More from Late-Breakers