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From Konstantin Margorin <rus...@gmail.com>
Subject Re: NoopSwapSpaceSpi and dynamically started caches
Date Thu, 18 Feb 2016 11:10:27 GMT
Yakov, thank you. Sounds good. I'll do this way.

On Thu, Feb 18, 2016 at 1:43 PM, Yakov Zhdanov <yzhdanov@apache.org> wrote:

> Konstantin,
>
> Here are my comments.
>
> 1. I would force same swap configuration on all servers. Therefore, I would
> add "checkClient" attribute to annotation which is "true" by default
> 2. I think all users should properly configure swap along the cluster if
> they want to handle possible memory overflow.
>
> --Yakov
>
> 2016-02-18 12:35 GMT+03:00 Konstantin Margorin <ruskim@gmail.com>:
>
> > Hi all.
> >
> > Sorry for asking again, but after some experiments I want to discuss
> > several options for grid swap policy. Some of them have odd side effects.
> > It's better to explicitly write them down to select the best solution.
> >
> > 1. Strict policy.
> > - @IgniteSpiConsistencyChecked(optional = false) used in FileSwapSpaceSpi
> > and NoopSwapSpaceSpi. Nodes with different swap providers could not
> coexist
> > in the grid.
> > - Cache with swap space could be start, only if all nodes in the grid has
> > FileSwapSpaceSpi provider enabled.
> > In this case if part of nodes in the grid use FileSwapSpaceSpi and other
> > part use NoopSwapSpaceSpi, than only random part of them will start. If
> the
> > first started node has FileSwapSpaceSpi, then all nodes with
> >  NoopSwapSpaceSpi will fail to start, and vice versa.
> > Interesting thing is that client nodes ( with
> Ignition.setClientMode(true))
> > should also has the same swap space provider as others nodes in the grid.
> > I.e. If nodes in the grid use FileSwapSpaceSpi, client will fail to start
> > if it use  NoopSwapSpaceSpi. That is strange, because client node does
> not
> > store any data, so swap policy is irrelevant to them.
> > Another interesting thing with client nodes is that client node with
> > NoopSwapSpaceSpi will never be able to start cache with swap enabled:
> > - if all nodes in the grid use FileSwapSpaceSpi, than client node simply
> > will fail to start
> > - if all nodes in the grid use NoopSwapSpaceSpi, than cache with swap
> will
> > not start on such nodes
> > 2. Soft policy
> > - @IgniteSpiConsistencyChecked(optional = true) used in FileSwapSpaceSpi
> > and NoopSwapSpaceSpi. Nodes with different swap providers could coexist,
> > warning is printed in case of different providers.
> > - Cache with swap space could be start, only if all nodes in the grid has
> > FileSwapSpaceSpi provider enabled.
> > In this case success of dynamic cache with swap creation depends on order
> > in which the nodes start. Suppose we have node with swap (nSwap), node
> > without swap (nNoSwap) and a client, who just after start creates dynamic
> > cache with swap (cSwap).
> > If nSwap and nNoSwap started before cSwap, than cSwap will fail to create
> > cache, because not all nodes in the grid support swap space.
> > If nSwap started first, than started cSwap. cSwap will create cache
> > succesfuly. After that nNoSwap will start. And we have configuration now,
> > when nodes with different swap policies are coexist in grid, but cache
> with
> > swap successfully started.
> > 3. Another option, initially suggested by Artem, is always use
> > FileSwapSpaceSpi if user doesn't provide SwapSpaceSpi explicitly.
> Probably
> > will get higher resources usage in this case.
> > 4. Leave it as now, but with logging:
> > - @IgniteSpiConsistencyChecked(optional = true)
> > - log when cache with swap enabled started and there some nodes without
> > swap in the grid
> > Which option should we choose?
> >
> >
> > On Tue, Feb 16, 2016 at 2:55 PM, Yakov Zhdanov <yzhdanov@apache.org>
> > wrote:
> >
> > > I think, yes
> > >
> > > --Yakov
> > >
> > > 2016-02-16 14:19 GMT+03:00 Konstantin Margorin <ruskim@gmail.com>:
> > >
> > > > Should we use optional=false in @IgniteSpiConsistencyChecked ?
> > > >
> > > > On Tue, Feb 16, 2016 at 1:15 PM, Dmitriy Setrakyan <
> > > dsetrakyan@apache.org>
> > > > wrote:
> > > >
> > > > > Sounds good to me.
> > > > >
> > > > > On Tue, Feb 16, 2016 at 2:13 AM, Yakov Zhdanov <
> yzhdanov@apache.org>
> > > > > wrote:
> > > > >
> > > > > > Let's require that all nodes should have same swap space SPI.
I
> > think
> > > > we
> > > > > > can put @GridSpiConsistencyChecked on file swap space SPI (any
> > other
> > > > > > suggestions?).
> > > > > >
> > > > > > --Yakov
> > > > > >
> > > > > > 2016-02-15 23:31 GMT+03:00 Konstantin Margorin <ruskim@gmail.com
> >:
> > > > > >
> > > > > > > Probably I can handle this ticket, but I want to clarify
one
> > thing.
> > > > > > >
> > > > > > > Suppose dynamic cache with enabled swap should be partitioned
> > > between
> > > > > two
> > > > > > > nodes with backups=1. First node started with FileSwapSpaceSpi,
> > > > second
> > > > > > with
> > > > > > > NoopSwapSpaceSpi.
> > > > > > >
> > > > > > > How cache should start in this case?
> > > > > > >
> > > > > > >
> > > > > > > On Mon, Feb 15, 2016 at 3:45 PM, Artem Shutak <
> > > ashutak@gridgain.com>
> > > > > > > wrote:
> > > > > > >
> > > > > > > > I've created a newbie issue for that:
> > > > > > > > https://issues.apache.org/jira/browse/IGNITE-2650.
> > > > > > > >
> > > > > > > > -- Artem --
> > > > > > > >
> > > > > > > > On Wed, Feb 10, 2016 at 8:53 PM, Dmitriy Setrakyan
<
> > > > > > > dsetrakyan@apache.org>
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > Artem,
> > > > > > > > >
> > > > > > > > > I like the option with proper exception in case
if a
> dynamic
> > > > cache
> > > > > is
> > > > > > > > > started with swap enabled while there was no
swap
> configured
> > in
> > > > > > Ignite.
> > > > > > > > >
> > > > > > > > > Starting FileSwapSpaceSpi all the time is not
a good option
> > as
> > > > user
> > > > > > > will
> > > > > > > > > face the same problem when trying to change to
a different
> > SPI.
> > > > > > > > >
> > > > > > > > > D.
> > > > > > > > >
> > > > > > > > > On Wed, Feb 10, 2016 at 4:39 AM, Artem Shutak
<
> > > > > ashutak@gridgain.com>
> > > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > > > Igniters,
> > > > > > > > > >
> > > > > > > > > > I've noticed an issue with NoopSwapSpaceSpi
and
> dynamically
> > > > > started
> > > > > > > > > cashes.
> > > > > > > > > >
> > > > > > > > > > We have the following logic on node start:
> > > > > > > > > >
> > > > > > > > > >             if (cfg.getSwapSpaceSpi() ==
null) {
> > > > > > > > > >                 boolean needSwap = false;
> > > > > > > > > >
> > > > > > > > > >                 if (cfg.getCacheConfiguration()
!= null
> &&
> > > > > > > > > > !Boolean.TRUE.equals(cfg.isClientMode()))
{
> > > > > > > > > >                     for (CacheConfiguration
c :
> > > > > > > > > > cfg.getCacheConfiguration()) {
> > > > > > > > > >                         if (c.isSwapEnabled())
{
> > > > > > > > > >                             needSwap = true;
> > > > > > > > > >
> > > > > > > > > >                             break;
> > > > > > > > > >                         }
> > > > > > > > > >                     }
> > > > > > > > > >                 }
> > > > > > > > > >
> > > > > > > > > >                 cfg.setSwapSpaceSpi(needSwap
? new
> > > > > > > FileSwapSpaceSpi() :
> > > > > > > > > new
> > > > > > > > > > NoopSwapSpaceSpi());
> > > > > > > > > >             }
> > > > > > > > > >
> > > > > > > > > > According to the code above, if IgniteConfiguration
> doesn't
> > > > > contain
> > > > > > > > cache
> > > > > > > > > > configurations or all configured caches
configured
> without
> > > > swap,
> > > > > > then
> > > > > > > > > node
> > > > > > > > > > will be started with NoopSwapSpaceSpi.
> > > > > > > > > > As a result in this case, when we start
dynamic cache
> with
> > > > > enabled
> > > > > > > swap
> > > > > > > > > > then actually swap doesn't work.
> > > > > > > > > >
> > > > > > > > > > There is simple workaround - user have to
explicitly set
> > > > > > > > FileSwapSpaceSpi
> > > > > > > > > > to configuration. But now, there is no any
warning or
> > > > exception.
> > > > > > > > > >
> > > > > > > > > > What we can do:
> > > > > > > > > >
> > > > > > > > > >    1. Throw an exception on dynamic cache
start (with
> swap
> > > > > enabled)
> > > > > > > > > >    if NoopSwapSpaceSpi is configured.
> > > > > > > > > >    2. Actually, I don't see why we need
NoopSwapSpaceSpi
> at
> > > > all.
> > > > > I
> > > > > > > > think
> > > > > > > > > we
> > > > > > > > > >    should configure FileSwapSpaceSpi always
if user
> doesn't
> > > > > provide
> > > > > > > any
> > > > > > > > > >    SwapSpaceSpi explicitly.
> > > > > > > > > >
> > > > > > > > > > Thoughts?
> > > > > > > > > >
> > > > > > > > > > Thanks,
> > > > > > > > > > -- Artem --
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

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