transmission "memory leak" in Mac OS

FAQ:Transmission Uses All the Free Memory

Inactive Memory

Description

Some Mac OS X users have reported that when they run Transmission, their system's Activity Monitor shows their Free memory keeps shrinking and their Inactive Memory keeps growing. This is sometimes mistaken as a memory leak, but is actually Mac OS X's normal behavior. As this  support.apple.com article explains, Inactive memory is not actually in use by Transmission and is recycled by the Mac OS X memory manager when other applications need it:

"This means you shouldn't worry when the Free memory is low. The only time Free memory should be high is right after the computer starts up. As you use applications or services, memory is used and transitions to Inactive. Applications that need more memory will take from the Inactive, but the Inactive is there just in case you need it again. If the combination of Free and Inactive is very low, then you might need more memory."

here is the article mention above:

Inactive:

This information is in RAM but it is not actively being used, it was recently used.

For example, if you've been using Mail and then quit it, the RAM that Mail was using is marked as Inactive memory. Inactive memory is available for use by another application, just like Free memory.  However, if you open Mail before its Inactive memory is used by a different application, Mail will open quicker because its Inactive memory is converted to Active memory, instead of loading it from the slower drive.

 FOR MORE

 as we know Mac is also kind of Unix, let's check some more info about Mac's Memory:

A few users have noticed that over time the amount of free RAM on their systems seems to go down, even if the active RAM size has not changed much. When looking at the System Memory pie chart in Activity Monitor, it's apparent that the "Inactive" memory segment seems to be growing. The question is whether or not this will affect performance, and what can be done about it?

There are four ways that RAM is described by the system: free, wired, active, and inactive.

1. Free RAM

   Being rather self-explanatory, this is the amount that has not been recently used by an application or system process.

2. Wired RAM

   This is the amount that must be kept active for the system to run. This RAM cannot be written to virtual memory on the hard disk.

3. Active RAM

   This is the current amount of memory besides wired RAM that is being used by system and user processes.

4. Inactive RAM

   This is the amount that has recently been used but is no longer required. It may have been used by a recently quit process, or by an active one that no longer needs it, and is not required for use. This RAM is essentially free RAM, with the exception that OS X has kept track of what has recently been loaded into it.

What does this mean?

Even though Activity Monitor shows a sliver of "free" memory available, this does not reflect the total amount of available RAM for use with new processes and applications. (Click for larger view)

The use of inactive RAM allows the system to more quickly relaunch those recently used processes, and therefore increase the speed of the system. Instead of having to load the RAM contents from the hard disk, the system will just convert the inactive RAM back to being active.

While this is beneficial to the system, it is a little deceptive when trying to determine the amount of free RAM on the system. If you are concerned about your system not having enough RAM, do not just look at the free RAM amount, but instead add up both the free and inactive RAM amounts.

As an example, on my PowerMac G5 with 2GB RAM, upon checking Activity Monitor I have a small sliver of free memory available (~33MB). At first glance this may appear as though I am completely out of memory; however, I have about 700MB of inactive RAM as well, meaning that overall I have 733MB available for use with new or reactivated system processes.

Despite this, some people still like to see green values and a larger free RAM amount. While we advise to allow the system to manage RAM for best performance, there are a couple of utilities you can use to make the green part of the memory pie chart as big as possible.

1. C.H.U.D. tools

   If you have Apple's Computer Hardware Understanding Developer tools installed (available from the Apple developer Web site--free, with registration), you should have the purge command installed, which can be run to free up some of the inactive memory.

2. iFreeMem

   The utility iFreeMem is useful for clearing out unused RAM by demanding as much RAM as possible from the system, forcing the system to write as much memory to disk as possible and otherwise clear the RAM, and reducing the overall memory footprint. We did a small review of iFreeMem, so be sure to check it out to see how it runs.

Keep in mind that the combination of free and inactive RAM is still not the total available RAM in the system, because if you put high memory demands on the system, other program's active RAM will be progressively written to virtual memory so it can be freed for use. The system cannot do this with wired memory, but it can do it with active memory.