Should PSCS2 Be releasing memory upon file closure

GA
Posted By
George_Austin
Sep 20, 2006
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264
Replies
9
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Closed
I have 1GB RAM, 630 MB available upon opening PSCS2. I open say 20 files totalling 100-200 MB. Task Manager shows available RAM reduced to about 50 MB. I close all open files. Available RAM now becomes 160MB. Why isn’t the original 630 available MB restored. I have to exit PS and return to get it back.

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John Joslin
Sep 20, 2006
Read up a bit on CS2 memory management.

It will release it if another application needs it.

Otherwise it makes sense to hang on to it.
CC
Chris_Cox
Sep 20, 2006
The memory is still in use by Photoshop, and will be reused if you open another file.

But there is no need to exit Photoshop, any unused memory will be paged out and other applications can still use whatever they need.
B
Brian
Sep 20, 2006
On Wed, 20 Sep 2006 12:49:41 -0700, George_Austin wrote:

I have 1GB RAM, 630 MB available upon opening PSCS2. I open say 20 files totalling 100-200 MB. Task Manager shows available RAM reduced to about 50 MB. I close all open files. Available RAM now becomes 160MB. Why isn’t the original 630 available MB restored. I have to exit PS and return to get it back.
Why not just leave memory management to Photoshop/the OS – unless and until it actually causes a problem? (other than ‘not looking right to me’)

B.

On the other hand, are different fingers.
GA
George_Austin
Sep 21, 2006
Are we looking at a deficiency in Windows Task Manager, since it fails to show the full available memory in the scenario cited?
CC
Chris_Cox
Sep 21, 2006
George – no, just that TaskManager can’t know what’s going on inside Photoshop.
GA
George_Austin
Sep 22, 2006
Chris—Yet Task Manager reacts to RAM usage in Photoshop and the number it posts for "available" memory must have some meaning—or is it spurious?
MD
Michael_D_Sullivan
Sep 22, 2006
George, Photoshop doesn’t lock up physical RAM so it can’t be used by other programs, it just requests memory allocations from the OS, which can grant allocations totaling more than physical RAM by using virtual memory (i.e., the page file, occupying disk space). Allocating large blocks of memory takes more time than using memory that’s already allocated, and freeing memory also takes time, and since PS is frequently in need of large blocks of memory either temporarily or for the long term, it does not free memory that’s been allocated for image data when that memory is not immediately needed, on the theory that it will likely need it again in the foreseeable future. If another program needs memory, it likewise asks the OS for it, and it will be provided from physical memory if available, else from virtual memory. Once the other program becomes active and PS is dormant, the OS tries to swap memory between RAM and virtual to ensure the active program’s memory is in RAM, and this may result in PS’s memory — used or unused — being swapped to disk. If you have a slow HD and not much memory, swapping large amounts of memory to disk may result in the computer seeming to be locked up for seconds, or even minutes. Once the swapping is done, the other application has all the RAM it needs. When it’s done, and you go back to PS, the OS will swap some or all of PS’s memory back from disk to RAM, which again may take a while.
CC
Chris_Cox
Sep 22, 2006
George – the task manager cannot see into Photoshop’s internal memory usage. It can only see the total memory usage at a particular time — not how that memory is being reused, not how that memory will be freed if the OS really needs it, and it doesn’t even tell you how that memory is being paged out by the OS. Photoshop will use memory up to the limit you set in preferences, and it will hold on to that memory to resuse it unless the OS really needs the memory (starts paging heavily), and the OS is always free to page out the inactive parts of Photoshop’s memory (the same as it does for any other application).
GA
George_Austin
Sep 22, 2006
Thanks to all for the very helpful clarifications

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