[infinispan-dev] rehashing hazard

[Manik Surtani]

On 22 Oct 2010, at 17:01, Mircea Markus wrote:

> 
> On 22 Oct 2010, at 15:17, Vladimir Blagojevic wrote:
>> 
>>>> 
>>>> The operations that need to be sequential are state transfer and tx log transfer. 
>>>> State is being *pulled* by C (thread running on C) and tx log is *pushed* by A (thread running on A). Two threads running in different VMs. 
>>> 
>>> Ok, this would be the issue then - this must have changed when Vladimir inverted the leave task to be a pull for the main state.  They both used to be pushes and sequential.
>>> 
>>> Perhaps the sequentiality can be re-established by a lock on the receiver?
>> 
>> Interested. What if C thread announce that it pulled state and upon reception of this message A drains the logs?
> 
> Is there any work that can be done in parallel? State transfer and log draining need to happen in sequence.
> If not what's the point of using two threads?

They are not just 2 threads - they are on 2 separate nodes.  State tfr is initiated by the receiver; tx log training by the sender.  Hence the different threads.  Modifying the protocol to allow for a state tfr ack message, as Vlad suggested, would work fine.

> One thread approach would be more maintainable and simple. I emphasise _maintainable_ because I've just debugged logs of state transfer and it's not the nicest thing to do.
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Manik Surtani
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