Clear inactive memory

I have 2 gigs of ram in my old desktop G5 and I'm running Final Cut Pro. My Activity Monitor is showing 1.44GB inactive and only 23.20mb Free. 428.88 MB is Active.

I understand that the Inactive memory is information that has been finished with that can be free'd up when another app needs it. I keep getting Out Of Memory messages up so why isn't the Inactive Memory freeing itself? The pie chart is almost 3/4 full! Why doesn't it use the RAM it has? Why does it only allow itself to use around a quarter or its memory? Is there a way of freeing it manually without having to restart?

2 gigs is fine usually...

Any help would be gratefully received!

PowerBook G4, Mac OS X (10.4.9)

Posted on Apr 17, 2008 10:34 AM

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18 replies

Apr 17, 2008 11:06 AM in response to Geraint Reynolds

Inactive memory is free memory. Inactive memory is just the memory that the computer used at one time but is no longer using. That memory can be used for other things later, but remains there for quick access just in case you need it again. The computer will automatically clear that memory for use as soon as it is required.

Memory management on the Mac is done automatically and intelligently. Inactive memory makes a lot of sense and there's no reason to clear it manually.

If you're running out of active memory from a leak in an application or process, you can use the Activity Monitor to end that process/application. Activity Monitor is also useful for identifying whether or not programs are hogging CPU usage or RAM.

Apr 17, 2008 11:04 AM in response to Devin Crutcher

That's accurate enough - but I'm curious about his 'out of memory' errors, specifically, where they're coming from.

There is a way to purge the memory caches, but it involves installing the Developer Tools. When the Dev Tools are installed, there's a program (/usr/bin/purge) which will flush the Inactive memory. It's intended for use by developers to put the system back into a state similar to just after a reboot.

Apr 17, 2008 1:13 PM in response to semicolons

If this is the old "Mac OS Purge", it will not work on Mac OS X.

If it's not that program, then IMHO it's unwise to posting a direct link to some unknown utility with no documentation or guarantee that it's not malware. Please post a link to the project page or some other site where any interested user can see information on what the utility does and from whom it comes.

Regards.

Apr 17, 2008 1:27 PM in response to varjak paw

Sorry, that web site's a work in progress, i.e. that's the only file I've uploaded so far.
Even so, I think your only option would be to trust me (or not download the file)... it shouldn't be too hard to forge a project page anyway.
It is the "purge" binary I found in /usr/bin/purge... I didn't even know it existed until today.
I certainly wouldn't advise running it on pre-10.5 systems, though, it was with the 10.5 software.

Apr 17, 2008 3:22 PM in response to Devin Crutcher

Wow, what a lot of answers! I'll take a look at the memory ceiling. Also I'll check the amount of space left on my internal too just to be sure. However, I won't get the purge tool as that seems to be a little beyond my capabilities but thank you anyway for the thought...

It is strange though that the inactive memory doesn't give it up to an app that clearly needs it. I'll check the ceiling for that...

Thanks for all the replies. I'll post when I get it worked out.

Apr 17, 2008 3:55 PM in response to varjak paw

I've used several versions of Final Cut, Express and Pro, and they all have this memory control.

Go to the *Final Cut Pro* menu, *System Settings...*, and then the *Memory & Cache* tab. There you'll see the *Memory Usage* sliders.

This really should be in the Final Cut section of these forums. Most of the people who have answered obviously don't know much about Final Cut.

Apr 18, 2008 7:49 AM in response to Devin Crutcher

That's not why I asked, Devin. I know that FCP has had the memory/cache controls for quite a while (back to the original Mac OS X version, Final Cut Pro 3, if recollection serves). My question was more about whether the OP is running an old version of FCP that might not be compatible with Leopard. If your comment about "Most of the people who have answered obviously don't know much about Final Cut. " was aimed at me, your assumption would be incorrect.

In any case, it seems as if the problem has been solved by the OP and turned out to be a corrupt sound clip.

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Clear inactive memory

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