No, Xmx only controls the maximum size of on-heap allocated memory.
The JVM doesn't manage/limit off-heap (how could it? it doesn't know
when it can be released).

The answer is that YARN will kill the process because it's using more
memory than it asked for. A JVM is always going to use a little
off-heap memory by itself, so setting a max heap size of 2GB means the
JVM process may use a bit more than 2GB of memory. With an off-heap
intensive app like Spark it can be a lot more.

There's a built-in 10% overhead, so that if you ask for a 3GB executor
it will ask for 3.3GB from YARN. You can increase the overhead.

On Wed, Sep 21, 2016 at 11:41 PM, Jörn Franke <jornfra...@gmail.com> wrote:
> All off-heap memory is still managed by the JVM process. If you limit the
> memory of this process then you limit the memory. I think the memory of the
> JVM process could be limited via the xms/xmx parameter of the JVM. This can
> be configured via spark options for yarn (be aware that they are different
> in cluster and client mode), but i recommend to use the spark options for
> the off heap maximum.
>
> https://spark.apache.org/docs/latest/running-on-yarn.html
>
>
> On 21 Sep 2016, at 22:02, Michael Segel <msegel_had...@hotmail.com> wrote:
>
> I’ve asked this question a couple of times from a friend who didn’t know
> the answer… so I thought I would try here.
>
>
> Suppose we launch a job on a cluster (YARN) and we have set up the
> containers to be 3GB in size.
>
>
> What does that 3GB represent?
>
> I mean what happens if we end up using 2-3GB of off heap storage via
> tungsten?
> What will Spark do?
> Will it try to honor the container’s limits and throw an exception or will
> it allow my job to grab that amount of memory and exceed YARN’s
> expectations since its off heap?
>
> Thx
>
> -Mike
>
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