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From Shawn Heisey <>
Subject Re: Solr configuration, memory usage and MMapDirectory
Date Mon, 06 Oct 2014 16:16:46 GMT
On 10/6/2014 10:07 AM, Simon Fairey wrote:
> Thanks and yeah I thought it might be crazy, the image is just the JVM memory usage you
get from the dashboard on the solr admin pages, the JVM on has what appears to be a light
grey then dark grey band then some blank space, those are the numbers I referred to if that
makes sense?
> Bit of quick ascii art to represent JVM memory usage image:
> ##########====----------------
> As I look now:
> -	Ends at 127.81GB
> = 	Ends at 67.30GB
> # 	Ends at 39.24GB
> My guess was that the light grey is used memory that hasn't been garbage collected and
the total bar is equivalent to the max heap setting?

If that's your JVM memory graph, then your max heap is *WAY* too big --
it's 128GB, and 67GB of that has actually been allocated.  Even with a
highly tuned GC, you're likely to have occasional long GC pauses ... and
if you haven't tuned your GC, those pauses could last for a minute or more.

As I said in my earlier reply, 4 to 6GB is probably enough for your max
heap.  The page that I linked on that reply describes using jconsole or
jvisualvm to connect to your running Solr instance and watch the memory
utilization graphs, to see just how much memory is required for the max


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