Hrm, two places I can think of:
One is in TabletServer.java itself. Look for the SortedMap members:
onlineTablets, unopenedTablets, and openingTablets. The onlineTablets is
essentially all of the Tablets that the TServer is hosting. You can use
this as a starting point to see where inside the TServer these tablets
are referenced.
For the assignment side, look for TabletGroupWatcher.java. This is
essentially the mechanism running inside the Accumulo Master which makes
sure that Tablets are online.
Mario Pastorelli wrote:
Hey Josh,
Thanks for the answer! I was wondering if you have some pointers in the
Accumulo code where I can read the implementation where the tablets
information are stored so that I can read it and understand if it will
give us problems eventually. We may have many tablets per server but we
have few servers which probably means that the number of tablets should
not be a problem.
Thanks,
Mario
On Tue, Sep 27, 2016 at 7:34 PM, Josh Elser <[email protected]
<mailto:[email protected]>> wrote:
Hi Mario,
There is no perfect answer here. It's going to be dependent on your
application latency requirements, data layout, and available
hardware resources.
In general, we recommend "hundreds of tablets" per tabletserver.
This should be a decent starting ponit. As you develop more and are
able to run some experimentations with your application, you might
find that more or less tablets are actually beneficial (for one
reason or another).
I'm not sure what a maximum number of tablets would be per tserver.
Probably 10's of thousands? It quite depends (again) on the hardware
resources available. The master is also a single entity managing the
assignment of each of those tablets -- eventually, just iterating
over tablets will take more and more time in the Master.
Additionally, each Tablet represents some additional amount of
memory in the TabletServer's JVM heap.
Sorry this isn't clear-cut answer -- maybe we can do a better job
encapsulating the important metrics in the docs somewhere? You're
certainly not the first to ask this question :)
- Josh
Mario Pastorelli wrote:
Hey,
I would like to know what is the maximum and recommended number of
tablets that we should have per machine. Right now is some
clusters we
have thousands of tablets and the number of tables will increase in
future. Eventually, we will have to add new machines to our
clusters and
a recommended number could help us decide the size of the new
cluster.
Thanks
Mario
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*software engineer*
Teralytics AG | Zollstrasse 62 | 8005 Zurich | Switzerland
phone:+41794381682
email: [email protected]
<mailto:[email protected]>
www.teralytics.net <http://www.teralytics.net/>
Company registration number: CH-020.3.037.709-7 | Trade register Canton
Zurich
Board of directors: Georg Polzer, Luciano Franceschina, Mark Schmitz,
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