Xms, Xmx, freememory and heapsize

[Lajos Moczar <lm...@galatea.com>]

Hi folks -

In January, there was an excellent post (with the same subject line) by 
Peter Hargreaves describing his experiences and recommendations for 
setting -Xmx, freememory and heapsize. One of his recommendations was 
that the value of heapsize should be somewhat less than that of -Xmx (he 
suggested the difference could be the value of freememory, as a good 
rule of thumb). The logic was that Cocoon needed some free memory to run 
the StoreJanitor. If -Xmx and heapsize were the same, you could 
theoretically have a situation in which Cocoon would not have enough 
memory to free memory.

But in some subsequent posts, I've seen it stated several times that 
-Xmx and heapsize should be the same. My question is whether anything 
changed in the 2.0.3 StoreJanitor implementation that makes Peter's 
suggestions irrelevant, or are they still valid?

Thanks.

Lajos

-- 
galatea.com
Cocoon training, consulting & support



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Re: Xms, Xmx, freememory and heapsize

[Vadim Gritsenko <va...@verizon.net>]

Lajos Moczar wrote:

> Hi folks -
>
> In January, there was an excellent post (with the same subject line) 
> by Peter Hargreaves describing his experiences and recommendations for 
> setting -Xmx, freememory and heapsize. One of his recommendations was 
> that the value of heapsize should be somewhat less than that of -Xmx 
> (he suggested the difference could be the value of freememory, as a 
> good rule of thumb).


If your heapsize is -Xmx value less freememory, it is same as specifying 
heapsize equal to -Xmx value and double the freememory value. Thus, you 
just have to carefully choose freememory parameter, that's it.

PS Seems that there is small bug in janitor (line 201), that's why 
heapsize should be at least one byte less then -Xmx value.

Vadim


> The logic was that Cocoon needed some free memory to run the 
> StoreJanitor. If -Xmx and heapsize were the same, you could 
> theoretically have a situation in which Cocoon would not have enough 
> memory to free memory.
>
> But in some subsequent posts, I've seen it stated several times that 
> -Xmx and heapsize should be the same. My question is whether anything 
> changed in the 2.0.3 StoreJanitor implementation that makes Peter's 
> suggestions irrelevant, or are they still valid?
>
> Thanks.
>
> Lajos



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