LimeWire hangs my Ubunutu

[Levander]

Osama I. Dosary wrote:

> I notice that the used Swap is ZERO. How can that be, when the Java 
> process is using 341MB of Virtual memory, with only 19MB resedent 
> memory. VIRT = SWAP + RES (from 'top' man-page), which means that 
> 322MB of swap must be used, so why isn't 'top' showing the swapping. 
> ... I'm confused. And is this related to the hangs?
>
Okay, there are a few things I know.

1.) The way the java virtual machine (jvm, aka the java binary that 
shows up in your top command) works is that when it starts up, it can 
request a giant chunk of memory from the operating system.  It doesn't 
use this chunk of memory initially, it just reserves it for use by 
programs written in Java that run on top of the jvm.  Java programs make 
use of this memory by instantiating Java objects, using the 'new' 
operator.  And, this heap size that is manage by the jvm can be 
controlled by the -Xmx and -Xms command line options to the java binary.

2.) Linux caches data that your system puts in memory.  And, these 
caches exist in  your RAM memory.  As you get closer and closer to the 
physical RAM limitations of your computer, the Linux kernel is designed 
to cache less memory.  The kernel opts to cache less in an attempt to 
keep your memory usage below the physical RAM limitations, so that 
hopefully you will have to swap memory usage out to disk less. 

Now, I may have gotten the words a little wrong, but the general idea of 
the above is correct.  Next, I start going out on a limb a little, 
guessing how this stuff works.

I'm guessing the disparity between your virtual memory use and your 
resident memory use isn't do to swap, as you noted when looking at the 
top output.  I'm guessing it's been requested by the jvm, but since the 
jvm hasn't actually used it yet, it hasn't actually been allocated by 
the Linux kernel. 

And, I can't imagine how this would cause your computer to hang.  It 
just tries to explain the disparity in the memory numbers you reported.

-Levander