Re: [jgroups-dev] How to implement/use flow control in JGroups

Ah, that makes sense.  Thanks!

Bela Ban wrote:
>
>
> Mike Jensen wrote:
>> I think I found a good solution here. Let me know if you see any
>> problems with this.
>>
>> I have set it up to use TCP, and removed the FC protocol. I then
>> configured TCP to not use the send queue. It seems that this allows us
>> to block (I assume from the kernel level from a quick inspection). I
>> then just added a thread pool to handle calling back to alert we are
>> ready to send more. Any worries about this setup?
>
> This probably works.
>
>> I tried to remove STABLE and NAKACK. As I did not understand a need for
>> these with the use of TCP (unless a server goes down, in which case I am
>> not concerned). But I continue to get warnings where it says
>> digest=null.
>
> NAKACK maintains vectors of seqnos received and delivered for every 
> member, e.g. 4:22:1:0:442. These are updated when a message is 
> received and are used to prevent duplicates and for retransmission of 
> missing messages. A new member needs to get the latest up-to-date 
> vector, so it'll know that the next message from P to be expected is 
> 42 (for example).
>
> Therefore GMS has a dependency on NAKACK; the stack won't start if you 
> remove NAKACK.
>
> STABLE is also needed to purge (stable) messages seen by everyone.
>
>
>


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