Memory management on the Mac

(Joe Stoner) #1

I spoke too soon regarding memory management in that I’m now running with only double digit MBits of memory until I run Memory Cleaner to free up circa 3MB of my memory. As Activity Monitor doesn’t show where this memory has either “leaked” from or “left hanging” I’ve no idea what Application or process is responsible:((
Re my iPhone my Battery Health (Beta) is ALWAYS 86%!!! My independent app shows the actual capacity varying between 1100mAh and 1400mAh!! It would seem that the (Beta) is VERY Beta:((

Apple Devices' Battery Life
(Al Varnell) #2

Memory cleaning has not been necessary since Apple introduced it’'s new memory management system with Mavericks. macOS now tries to keep memory as full as possible to prevent having to constantly read the same code from your drive all the time. Clearing it actually slows things down as it requires the OS to rebuild those cache files that you just removed.

In Activity Monitor’s Memory tab, look at the “MEMORY PRESSURE” graph at the bottom. As long as it stays green there aren’t any memory issues at all. If it stays red then it suggests you need to purchase more RAM if you can.

Apple guidance can be found at and click on the “Memory” box.


(Joe Stoner) #3

Hi Al
Apple’s memory management has a LONG and not always spotless history so Mavericks NEW MM is just it’s latest incarnation and will not be it’s last. Cleaning my memory SEEMS to speed up my MBP, which is rammed to the hilt at only 16GB (I swear that 32GB was the max that I was checking on the price for when I could afford an upgrade!)
As for “macOS now tries to keep memory as full as possible to prevent having to constantly read the same code from your drive all the time”. This applies to Applications that you’ve quit (according to the notes) as I do not use a multiplicity of Applications most of the time the available memory (according to Memory Keeper and Cleaner) just “leaks” away over an hour or so of using just the same Applications. Filling RAM with anything extra is counter productive for using (as I very occasionally do these days) really memory hungry applications like Photoshop which is why I invested in 16GB in the first place.
I now have over 300 Processes using memory at the moment!! When I re-start I’ll check on the number again.

(Al Varnell) #4

Hundreds of thousands of Mac users and virtually all Mac Techs will disagree with you about the use of a Memory Cleaner, but suit yourself.

Apple always states a conservative estimate on RAM capacity, usually because at the time of R&D before manufacturing, larger RAM chips were to available.

MacTracker, OWC and Crucial can give you the real number.


(Joe Stoner) #5

The re-start included Photoshop and Bridge and my memory “leaked” away to double digit MBs almost before the system stabilized! I now have nearly 400 Processes using memory!

(Al Varnell) #6

And again I have to say so what. That’s perfectly normal and what most of us see all the time. If RAM wasn’t mostly full then the OS isn’t doing it’s job. Leaks may or may not be the reason, but when the OS need RAM it will make room for it. First using compression, then freeing application cache and finally freeing System cache. Only then will the graph turn Red, which is the ONLY indication of a memory issue.

Also, I thought this discussion was supposed to be about Battery Life, and memory management doesn’t really play a part in that.


(Joe Stoner) #7

Last on memory Al all links say the same as I’d found… 16GB IS the Max for me.
My latest TechTools Pro run shows my battery at 710 cycles so it’s not increasing as rapidly as it was AND my MagSafe seems to behaving itself and charging whenever it’s connected! I’ve not changed the way that I used my MBP but I have updated my system 10 days or so after announcements of availability.
Regarding my iPhone I’ve updated its iOS regularly BUT my Battery State is frozen at 84% which I DO NOT believe!

(@lbutlr) #8

Free Memory is wasted memory. You do not want free memory, and running an sort of “cleaner” will actually make your device run worse.

(Joe Stoner) #9

Are we discussing quantum computing or actual RAM holding ones & zeros in a pattern that has to be wiped before writing another pattern of ones & zeros. Having RAM full of either random patterns or redundant patterns doesn’t make sense as a sane memory management tactic. Now regular polling of and clearing out of RAM would seem to me to be not a waste of an operating systems cycles. All I can say is that my system crawls when I have 10 or 20 MB of free memory.
Also what’s the point of fitting extra RAM IF it’s just to fill up with dross?

(Al Varnell) #10

This are not random patterns. Used memory only has known data or code that is needed to run the OS and applications. And there is no wipe before writing new data, it’s simply marked as available and immediately written to.

If you won’t believe us or Apple, maybe this arsTECHNICA explanation will help you understand the basics.

Also, you still haven’t shared with us what the MEMORY PRESSURE graph is telling you.


(Joe Stoner) #11

Did you mean to send me a link(<>) Al?

(Al Varnell) #12

Sorry, I forgot that I can’t use corner brackets here