如何确定初始堆的大小和最大堆

Question

I want to change initial heap (-xms) and max heap (-xmx) size in eclipse indigo but I don't know the correct size that must allocated for heap. What are the considerations in determining the size that fit with the application that used?

Answer 1

There are several things to consider.

First of all - you say that you want to "change" initial sizes of heap and max heap. So, the question is simple: why do you need it? For example, some time ago I had to change my IntelliJ IDEA's heap settings to higher values, because it couldn't handle my project. Or do you have some specific reason to change heap size?

Eclipse's heap settings can be located in eclipse.ini file. At least in my Eclipse Juno, eclipse.ini contains:

-Xms40m
-Xmx512m

So, initial size of heap is 40 MB, but it can resize up to 512 MB. Check your eclipse.ini - are numbers the same?

And, as I asked previously, could you please tell me, why do you want to change heap settings?

EDIT

Nice tutorial at Eclipse's Wiki about how to change heap size in Eclipse .

Answer 2

initial heap size Larger of 1/64th of the machine's physical memory on the machine or some reasonable minimum. Before J2SE 5.0, the default initial heap size was a reasonable minimum, which varies by platform. You can override this default using the -Xms command-line option.

maximum heap size Smaller of 1/4th of the physical memory or 1GB. Before J2SE 5.0, the default maximum heap size was 64MB. You can override this default using the -Xmx command-line option.

you can increass by

export _JAVA_OPTIONS="-Xmx1g" java -jar jconsole.jar & Picked up _JAVA_OPTIONS: -Xmx1g

or

Setup JAVA_OPTS as a system variable with the following content:

JAVA_OPTS="-Xms256m -Xmx512m"

After that in a command prompt run the following commands:

SET JAVA_OPTS="-Xms256m -Xmx512m"