Garbage Collector question?

[yogesh@xxxxxxxxx (Yogesh Pandeya)]

Hi Monaco,
Its not memory pool, it is Object pool. The pool manager holds those =
objects for you and gives you on request. You use them and return them =
back to the manager. During the initialization, those objects are =
created and stored with the manager. You must take care to return those =
objects to the manager after using them.

For example, suppose you need an array of N objects for some processing =
which you do repeatedly. If you create this array everytime you do the =
processing, it will result in poor time as well as memory performance as =
they will have to be garbage collected after use. To save time and =
memory, what you do is that you request the pool manager to create an =
array of N objects for  you during initialization. Whenever you need to =
use the array, you request the manager to pass it on to you, you use it =
and pass it back to the manager so that you get it next time you need =
it. This way you save on time and memory.

Hope this helps you,
cheers,
yogesh
-----Original Message-----
From:	Luigi Monaco [SMTP:lm@xxxxxxxxx]
Sent:	Tuesday, November 30, 1999 8:36 PM
To:	Yogesh Pandeya
Subject:	RE: Garbage Collector question?

hi yogesh,
? how would you create yourself a memory pool for possible allocation
without dealing with vm options in startup
Zdys
At 07:14 PM 11/30/99 -0000, you wrote:
>Hi Shrihari,
>When you start a VM, it gets some initial memory from the system. It
differs from VM to VM and version to version. That is the default size =
of
the VM's memory. You can change the initial memory using -Xms option =
while
starting the VM.
>Now whenever you do a "new", it is a *potential* trigger for gc, but =
not
always neccessary. when the VM starts running out of memory because of
object creation, it tries to first collect some garbage and allocate =
memory
to objects. If it still requires more memory, it gets it from the
system(underlying OS) and runs with higher memory. this newly acquired
memory is not returned back to the system till VM runs. You can check =
this
by using runtime total memory and free memory. You will find the total
memory increasing as you create more objects without assigning it to =
null.=20
>
>The idea behind object pool is that if you know that you are going to
create large number of objects again and again for some processing, you
create a pool (or bucket) of objects at the time of initialization. =
during
run time you take the objects from the bucket, use them for your =
purpose,
and return them to the bucket. For this you have a pool manager which is
initialized in the begining and you request the manager to create =
objects
(you will need down the line during run time) during initialization. =
During
run time you request those objects from the manager, initialize them as
needed, and return them to the manager after use. This saves a lot of =
you
time for object creation. The objects created in the pool are not
temporary. They satay with you for the application lifetime unless you =
have
methods in the manager to specifically destroy them.(setting them to =
null)

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