How would you tune a 32Gb RAM box running one Cosmo instance
and MySQL?
Say, hypothetically, you had a big honking server you wanted
to deploy a
large instance of Cosmo onto it; maybe call it Chandler
Hub.
There's a whole art to tuning Java VMs; I am admittedly
deficient in
this art. I can spend weeks/months googling for the finer
points, but I
was hoping to get some insight here.
Of course, the settings are also JVM-dependent; we're
intending a
JRockit deployment, so I'll use their names for things.
I assume we need to decide on the following parameters for
Hub:
* Minimum heap size (initial probably set maximum heap)
* Maximum heap size (has a 1Gb max out of the box?)
* Nursery size (less than max heap of course>
* -server (decision made, I assume)
* -Xverbose:memory (show paging)
* -Xgcpause (document collection pause durations)
* Garbage thread priority (parallel, throughput, gencon?)
* Thread stack size (defaults to 320KB)
* Any other garbage collection settings
* Any other general settings?
My understanding is that setting the heap very large (20Gb)
will result
in long pauses during collection, which we want to avoid.
(Java is
probably going to be conservative in its memory use, with
most of the
surplus going to MySQL.)
We apparently could also go with a dynamic GC setting by
setting a
"-Xpausetarget" of a specific time say 300ms.
Of course many of these options are interdependent.
On doing a little reading, I guess I remember more about
this than I
thought, but are there any books people have read with good
tuning sections?
Back in cosmo-demo days, we used:
-Xns:500m -Xms:700m -Xmx:700m -server -Xgcpause -Xgcreport
-Xverbose:memory
It just occurred to me that we could do another "Java
Runtime Analyzer"
run; we did that back in the cosmo-demo days to try to track
down some
performance bugs, but maybe there's some GC/heap info in it
too.
There's another thread needed about MySQL tuning, but that
one might be
a little more straightforward.
-- Jared
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