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Something running in background?

I have a "late 2012" IMac running OS 10.10.5. Lately I have noticed at times it will run much slower when attempting to work on line; and even if I am not browsing but the computer is on I can look at the modem and the "internet" light is flickering rapidly. When this is happening, other devices connected through air port are also slower. This continues even when I "sleep" the IMac, but will stop if I turn it completely off and reboot the modem. Is there something active in the background, trying to run something on line? I know historically antivirus software has not been recommended for these, but lately I seem to remember hearing that may no longer be true. Or is there something else processing in a loop that is fixable? Thanks in advance for answers.

iMac (21.5-inch, Late 2012), OS X Yosemite (10.10.5)

Posted on Feb 8, 2016 10:49 AM

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4 replies

Feb 8, 2016 12:53 PM in response to Cmreider

When you see a beachball cursor or the slowness is especially bad, note the exact time: hour, minute, second.

These instructions must be carried out as an administrator. If you have only one user account, you are the administrator.

Launch the Console application in any one of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

The title of the Console window should be All Messages. If it isn't, select

SYSTEM LOG QUERIES All Messages

from the log list on the left. If you don't see that list, select

View Show Log List

from the menu bar at the top of the screen.

Each message in the log begins with the date and time when it was entered. Scroll back to the time you noted above.

Select the messages entered from then until the end of the episode, or until they start to repeat, whichever comes first.

Copy the messages to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.

The log contains a vast amount of information, almost all of it useless for solving any particular problem. When posting a log extract, be selective. A few dozen lines are almost always more than enough.

Please don't indiscriminately dump thousands of lines from the log into this discussion.

Please don't post screenshots of log messages—post the text.

Some private information, such as your name, may appear in the log. Anonymize before posting.

When you post the log extract, you might see an error message on the web page: "You have included content in your post that is not permitted," or "The message contains invalid characters." That's a bug in the forum software. Please post the text on Pastebin, then post a link here to the page you created.

If you have an account on Pastebin, please don't select Private from the Paste Exposure menu on the page, because then no one but you will be able to see it.

Feb 8, 2016 12:55 PM in response to Cmreider

Or is there something else processing in a loop that is fixable?


Not on that Mac. When a Mac is sleeping, it is doing exactly nothing other than to wait for an event that would cause it to wake from sleep. That event is external and does not not originate with the Mac. You can also disable it if you wish. Therefore whatever modem activity you are describing when the iMac is asleep is unrelated to that iMac. Look to your other Internet-connected devices for the cause. Only you can know what those devices are.


Do not install non-Apple "anti-virus" software, unless you want real problems. Please read Effective defenses against malware and other threats.

Feb 8, 2016 2:08 PM in response to John Galt

Hi, I have a similar problem, the hard drive is constantly doing something when I am not typing and the machine is very slow. I have had to force quit several programs inc. Mail/Firefox/iTunes all of which hung. This has been going on for several hours so I cannot identify a start/stop period. I have opened console with 4000 messages. I would be grateful for advice on how to spot possible clues amongst the tons of data.


Mac does not sleep, screen goes dark but hard drive is still working.


Thanks


Alan

Feb 8, 2016 6:34 PM in response to alanmclean

Hi Alan, the symptoms may be similar but the cause is almost certain to be completely different and unrelated to the subject at hand. Please post a new Discussion. Whereas other user-to-user product support or discussion sites might consider doing that inappropriate, posting your own Discussion really is the best way to receive competent and timely assistance from this one. Thanks!


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