On Fri, Oct 8, 2010 at 4:54 AM, Jedd Rashbrooke
<jedd.rashbrooke@imagini.net> wrote:
> On 8 October 2010 02:05, Matthew Dennis <mdennis@riptano.com> wrote:
>> Also, in general, you probably want to set Xms = Xmx (regardless of the
>> value you eventually decide on for that).
>
> Matthew - we'd just about reached that conclusion! Is it as big an
> issue for clusters that are up for days at a time, with maybe Xmx:3G?
> I'd kind of assumed that it'd get to its max pretty quickly. I haven't
> been watching that with jconsole, but might watch it on the next startup.
The main reason to set Xms=Xmx is so mlockall can tag the entire heap
as "don't swap this out" on startup. Secondarily whenever the heap
resizes upwards the JVM does a stop-the-world gc, but no, not really a
big deal when your uptime is in days or weeks.
--
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com
|