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From Dmitriy Setrakyan <dsetrak...@apache.org>
Subject Re: PageMemory approach for Ignite 2.0
Date Tue, 03 Jan 2017 17:11:41 GMT

I would qualify the need for PageMemory as strategic for Apache Ignite.
With addition of SQL Grid component, Ignite can now also satisfy in-memory
database use cases, which are very space consuming and require a new memory
management approach. Basic distributed hash map is not going to work for
such use cases.

Once PageMemory becomes stable and fast, I don't believe we can afford to
maintain two types of memory management in the project. It will be just too
time consuming. On top of that, the old approach will simply not be needed

I am OK with maintaining 2 implementations, assuming we can have a good
abstraction for the memory management.However, even in that case, we should
all weigh whether it makes sense to spend time on migrating the current
on-heap implementation to use these new memory APIs.


On Sun, Jan 1, 2017 at 10:47 PM, Vladimir Ozerov <vozerov@gridgain.com>

> Dima,
> Performance is a serious concern, but not the main one. My point is that
> standard users working on commodity hardware and requiring only in-memory
> mode simply do not need page memory. They need distributed HashMap. We
> already have it. It is fast, it is stable, it have been tested rigorously
> for years. It does what users need.
> PageMemory approach targets high-end deployments which is hardly represents
> majority of our users. Less than 10% I think. Or may be <5%, or even <1%.
> This is who may benefit from page memory. Others will benefit nothing
> except of additional layer of indirection, drop in performance, risks of
> instability. And problems with capacity planning, because it is much harder
> to plan two memory regions properly than a single one.
> I talked to Alexey Goncharuk some time ago, and he told it is not a big
> deal to abstract out PageMemory. Alex, please confirm. I encourage everyone
> to stop thinking of dropping "old" before you have built "new" and
> confirmed that it is better.
> Let's ensure that new approach is well-abstracted, add it to 2.0, let it
> maturate for 1-2 years, and then think of dropping current approach in 3.0.
> This sounds much better to me.
> On Sun, Jan 1, 2017 at 10:42 AM, Denis Magda <dmagda@apache.org> wrote:
> > Sorry, just recalled that Unsafe is not JNI based. However, my previous
> > point of view still remains the same.
> >
> > > On Dec 31, 2016, at 11:39 PM, Denis Magda <dmagda@apache.org> wrote:
> > >
> > > JNI-based Unsafe that also brings performance hit
> >
> > —
> > Denis
> >
> >

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