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From Jason Harvey <>
Subject Re: Bizarre side-effect of increasing read concurrency
Date Sat, 02 Apr 2011 03:27:18 GMT
On further analysis, it looks like this behavior occurs when a node is
simply restarted. Is that normal behavior? If mark-and-sweep becomes
less and less effective over time, does that suggest an issue with GC,
or an issue with memory use?

On Apr 1, 8:21 pm, Jason Harvey <> wrote:
> After increasing read concurrency from 8 to 64, GC mark-and-sweep was
> suddenly able to reclaim much more memory than it previously did.
> Previously, mark-and-sweep would run around 5.5GB, and would cut heap
> usage to 4GB. Now, it still runs at 5.5GB, but it shrinks all the way
> down to 2GB used. This behavior was consistent in every machine I
> increased read-concurrent on.
> Any thoughts on why this behavior changed? No other diagnostics
> appeared to correlate to the concurrency change, besides thread count.

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