Caldarale, Charles R wrote:
>
>> From: Alexey Solofnenko [mailto:[EMAIL PROTECTED]
>> Subject: Re: Tomcat with 8 GB memory
>>
>> I was under impression that GC does not scale linearly. That
>> means one 8GB process will be slower than two 4GB processes.
> Not true. The time of a full GC using modern algorithms depends mostly
> on the number and type of live objects, not the amount of heap space.
> The number and type of live (reachable) objects stays relatively
> constant for most application once the ramp-up period is over.
> Consequently, running a single JVM with the largest heap you can fit in
> the process space is the most efficient from a GC point of view. (Of
> course, there are plenty of other reasons not to put all your eggs in
> one basket.)
>
There are several factors that matters for GC: number of objects,
number of object references, size of objects. All matters! As number of
objects get bigger, it tends to have more reference. Size of objects?
This does matter when heap compression is involved,
objects have to be moved.
In addition, keep in mind that your heap memory is on virtual memory.
While doing GC analysis, if you don't have enough main memory, this
can create caos.
I have a system that create a number of objects that allocate sizable
memory. When it hit a simple write (may read also) operation, it then goes
mad! This happens on Windows! But I don't know what's wrong with it.
For about 10 ~ 20 minutes, it stop everything and does I/O only
until the dust clears!
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