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From Christopher Schultz <ch...@christopherschultz.net>
Subject Re: [OT]RE: Maximum memory that can be assigned to Tomcat on windows platform
Date Fri, 02 Dec 2011 01:39:24 GMT
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Mark,

On 12/1/11 9:50 AM, Mark H. Wood wrote:
> On Thu, Dec 01, 2011 at 12:38:01PM +0100, Mikolaj Rydzewski wrote:
>> On the other hand, increasing java heap size is not always the
>> best option. It heavily depends on memory usage pattern in your
>> application. In general: the bigger heap, the longer GC will
>> run.
> 
> I was thinking that someone should bring this up.  When a program
> uses unexpectedly huge amounts of memory in practice, the *first*
> thing to consider is:
> 
> 1.  does it actually need that much?

+1 !!

> 2.  ...or is it leaking dynamically created objects? 3.  ...or has
> cheap allocation and garbage collection lured me into doing
> something suboptimal, like sucking down an entire database table
> into an array or list and then walking it sequentially, when I
> could have used an iterator and let the DBMS code work out 
> near-optimal buffering?
> 
> IOW "is my problem fundamentally this big, or is something else
> going on?"

The 2 times our production servers have suffered OOMEs, it's been
because we were running with fairly small, (intentionally) restricted
heaps (64MiB at first, then 192MiB) and our traffic simply increased
beyond our heap size: we had a legitimate reason to increase the heap
size (and plenty of physical RAM available to do it).

- -chris
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