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From Leif Hedstrom <zw...@apache.org>
Subject Re: ATS freebsd memory usage
Date Mon, 13 Feb 2012 15:41:17 GMT
On 2/13/12 2:02 AM, ming.zym@gmail.com wrote:
> that looks like you are in the issue of TS-1006:
> https://issues.apache.org/jira/browse/TS-1006


Hmmm, so, I personally never see this unbounded growth myself. What is it 
that makes it grow out of bounds like this? It can't just be the RAM cache, 
is it? Is there a bug in how it calculates memory usage vs what is allocated 
for it?

There is no surprise that memory isn't free, the freelist doesn't work like 
that (obviously). Meaning, if the system at some point needed 1GB of RAM, 
and it's now on the freelist, it would never go below 1GB of RAM usage. The 
questions are:

1) Is there a leak in the RAM cache, or some other bug that prevents it from 
limiting the memory usage as per the records.config settings?

2) Or is there a "leak" in the freelist, where objects that are put on the 
freelist are not reused, and instead, we allocate new ones?


I think we have to try to understand why this is happening, what sort of bug 
it is, and how it happens. Blindly freeing things from the freelist doesn't 
seem right to me (it's goes against the design and purpose of it). Hence, 
understanding why the freelist is allowed to grow out of bounds is the first 
step.

I do agree that it could be useful to have an (optional) feature where we 
periodically reduce the various freelists that we have, so that we can 
reclaim some memory from extreme "spikes" in usage. But that can't be the 
solution to this problem I don't think?

-- Leif


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