macOS: Renice processes that behave poorly (we can have nice things!)
- Requirements
- Quick Start
- What Is It For?
- How Does It Work?
- How to Install
- Customizing the Schedule
- Customizing the Process Names
- References
- macOS (tested with 10.14.6 (Mojave))
- Access to
sudo("Allow user to administer this computer") - Shell prompt
./install.sh --with-crontab --dry-run
nice-things --help
macOS likes to do some things---for example, Spotlight indexing---while a Mac is turned on. Sometimes, these activities happen while we humans want to do other things with our Macs, but the activities are "bad neighbors" and use too many system resources (like CPU).
If your Mac is running an anti-virus scanning program, for example, it may be overexuberant, taking all the available CPU to get through a scan as fast as possible.
nice-things helps by changing the scheduling priority of certain processes to make them "less important" and give CPU time back to the things we want to do.
Summary:
$ nice-things --dry-run
[DRY-RUN] Would run:
+ sudo renice 20 -p 83244 83245 83247 83248 83249
$nice-things does the following:
- Find the processes whose names match the ones asked for.
- Check each found process's priority.
- If a process's priority is "too important", change its priority to make it less important.
- If you want, write messages to the system log indicating what it's doing.
To do this, nice-things uses CLI commands called pgrep (to find matching processes), ps (to find a process's priority) and renice (to change a process's priority).
If you just run nice-things from the command line, this happens once:
$ nice-things
me@my-macbook-pro's password:
Oct 13 16:46:59 nice-things[86905] <Notice>: + sudo renice 20 -p 86412 86413
$nice-things can also be run on a schedule in the background, using cron -- for example, running every minute or every 5 minutes. This way, nice-things can set the scheduling priority for processes that start when you're not at your Mac, or when you're already in the middle of doing something else.
nice-things comes with an installation script, called install.sh, which
requires a shell prompt in a Terminal window.
You can see what install.sh will do without doing it by using the
--dry-run option:
$ ./install.sh --dry-run
me@my-macbook-pro's password:
[DRY-RUN] OK: Directory exists: /usr/local
[DRY-RUN] OK: Directory exists: /usr/local/bin
[DRY-RUN] Would install: /usr/local/bin/nice-things
[DRY-RUN] Would run:
+ sudo install -m 0755 -o 0 -g 0 bin/nice-things.sh /usr/local/bin/nice-things
$To install just the nice-things command, use:
./install.sh
If you want to install it somewhere besides /usr/local/bin, you may supply a
different prefix. For example:
./install.sh --prefix /opt/nice-things
To install both the nice-things command and the crontab schedule for
periodically running in the background, use:
./install.sh --with-crontab
For example:
$ ./install.sh --with-crontab
me@my-macbook-pro's password:
OK: Directory exists: /usr/local
OK: Directory exists: /usr/local/bin
Installing: /usr/local/bin/nice-things
+ sudo install -m 0755 -o 0 -g 0 bin/nice-things.sh /usr/local/bin/nice-things
Retrieving root's crontab ...
Adding the following to root's crontab:
--- /path/to/temp/dir/install-nice-things.uiHuYvtC 2020-10-13 16:50:32.000000000 -0700
+++ /path/to/temp/dir/install-nice-things.dV7UZEHz 2020-10-13 16:50:32.000000000 -0700
@@ -0,0 +1,4 @@
+
+MAILTO=""
+
+* * * * * /usr/local/bin/nice-things --quiet
+ sudo crontab -u root /path/to/temp/dir/install-nice-things.dV7UZEHz
$macOS may ask you something like:
“Terminal” would like to administer your
computer. Administration can include
modifying passwords, networking, and
system settings.| Don't Allow | OK |
If you want the crontab changes to take effect, press OK.
By default, nice-things is scheduled to run once a minute. If you want to
change the frequency to, for example, every five minutes, you can edit root's
crontab:
sudo crontab -u root -e
and change the first time/date field to */5:
*/5 * * * * /usr/local/bin/nice-things --quiet
Then save and exit.
See the [crontab manual page][] for more information about how to customize the schedule for a background "cron job".
The default process names that nice-things reprioritizes are:
- iCoreService
- mdworker
You can change those by supplying a different list of process names or
patterns as command-line arguments to nice-things. For example, if your
Google-based browser runs too fast for you:
nice-things --dry-run 'Google Chrome'
That works whether you're using nice-things at your Bash or Zsh prompt or as a periodic cron job.