On 1/26/12 5:43 PM, Dan Berindei wrote:
> On Thu, Jan 26, 2012 at 7:17 PM, Manik Surtani<[email protected]> wrote:
>> On 26 Jan 2012, at 16:05, Sanne Grinovero wrote:
>>
>>> On 26 January 2012 10:36, Manik Surtani<[email protected]> wrote:
>>>> Dan,
>>>>
>>>> Looking through what we currently have, given the blocking nature of state
>>>> transfer, I wonder if we can improve on it by pausing the state transfer
>>>> from time to time to flush waiting transactions? I.e., if state transfer
>>>> is in progress and a write command or transaction is waiting for it to
>>>> finish, and since state transfer is chunked anyway, perhaps to let a few
>>>> transactions through in between transferring chunks?
>>> Wondering about my proposal about transfering values separately from
>>> locks not being easier to implement? Or likely same effort, but
>>> better..
>> Well, thats what I want to try and understand. If periodic flushing is
>> easier/quicker/less risky to implement, I think we could do it for 5.2.0. :)
>>
> I don't think it would be any easier/less risky - the moment we allow
> transactions to go through our data container iterator is no longer
> valid and we could e.g. push data that's been already deleted on the
> old owner.
>
> The only improvement to the current blocking state transfer that I
> think would be easy enough is
> https://issues.jboss.org/browse/ISPN-1731 - when we acquire a key lock
> we'd have to try first with 0 timeout and then when we wait with a
> non-zero timeout we'd have to register our thread so that state
> transfer can interrupt it.
>
> In fact, since non-blocking state transfer also requires threads to
> line up at a barrier at some point, this should help non-blocking
> state transfer as well.
>
> Actually there is something else, but I'd consider it more of a bug.
> With optimistic transactions we retry the prepare after it failed to
> acquire the state transfer lock, but with pessimistic transactions I'm
> not sure the retry works properly.
>
>> Sanne, have you documented your design on separate transfer of state vs
>> locks on the wiki somewhere? I'd be curious to see what Paolo and the
>> others at INESC and CINI think about it as well. :)
>>
> I wrote a paragraph about it here:
> https://community.jboss.org/wiki/AsymmetricCachesAndManualRehashingDesign
> I'm not sure if Sanne validated it...
>
> Cheers
> Dan
Thanks Manik, Dan.
In fact this is something very interesting for us (especially
Sebastiano, who's reading in cc).
Although I cannot promise that we'll be able to be very quick in sending
a feedback as we're swamped with several deadlines in this moment.
Cheers,
Paolo
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