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From "Ramkumar R. Aiyengar" <>
Subject Re: Scaling to large Number of Collections
Date Sun, 31 Aug 2014 15:53:15 GMT
On 31 Aug 2014 13:24, "Mark Miller" <> wrote:
> > On Aug 31, 2014, at 4:04 AM, Christoph Schmidt <> wrote:
> >
> > we see at least two problems when scaling to large number of
collections. I would like to ask the community, if they are known and maybe
already addressed in development:
> > We have a SolrCloud running with the following numbers:
> > -          5 Servers (each 24 CPUs, 128 RAM)
> > -          13.000 Collection with 25.000 SolrCores in the Cloud
> > The Cloud is working fine, but we see two problems, if we like to scale
> > 1.       Resource consumption of native system threads
> > We see that each collection opens at least two threads: one for the
zookeeper (coreZkRegister-1-thread-5154) and one for the searcher
> > We will run in "OutOfMemoryError: unable to create new native thread".
Maybe the architecture could be changed here to use thread pools?
> > 2.       The shutdown and the startup of one server in the SolrCloud
takes 2 hours. So a rolling start is about 10h. For me the problem seems to
be that leader election is "linear". The Overseer does core per core. The
organisation of the cloud is not done parallel or distributed. Is this
already addressed by or is
there more needed?
> 2. No, but it should have been fixed by another issue that will be in

Note however that this fix will result in even more temporary thread usage
as all leadership elections will happen in parallel, so you might still end
up with these out of threads issue again.

Quite possibly the out of threads issue is just some system soft limit
which is kicking in. Linux certainly has a limit you can configure through
sysctl, your OS, whatever that might be, probably does the same. May be
worth exploring if you can bump that up.

> - Mark

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