[Pvfs2-developers] Re: BMI TCP socket close for sock buf size

[Sam Lang]

On Jul 16, 2006, at 3:57 PM, Walt Ligon wrote:

>
> Hey guy, I'm trying to understand why the msgpairarray stuff is in the
> common directory and has this stuff to let it work with both the  
> client and the server (and in fact gets compiled with both the  
> client and the server) when it doesn't appear to get used by the  
> server at all.  Is it getting used in some tricky way I overlooked

I don't think so.  I haven't seen it used anywhere on the server.

> , or is this an historical artifact, or was it supposed it might  
> get used, even though it never did?
>

Right.

> Unless there's a good reason otherwise I'm inclined to move it into  
> the client code.

Seems reasonable.  BTW, we've talked about this already, but since  
the msgpairarray state machine is the current topic, I'll reiterate  
some of my ideas.  Its written in such a way that at present can't be  
used by sys-io.sm.  The problem is that it blocks (doesn't complete)  
waiting for a response from all of the servers in the array.  In the  
case of sys-io, we want to fire off the flows to the servers once we  
get responses from them.  With the new concurrent state machine code  
in place, I could imagine the msgpairarray being a set of concurrent  
nested state machines, that in the normal case all just wait for  
completion before returning to the parent.  In the case of sys-io  
though, it seems like we could leverage that by allowing groups of  
concurrent machines to be chained together, and instead of waiting  
for all of the concurrent machines to finish (each msgpairarray),  
allow the completion of one to be the beginning of another nested  
machine in a different grouping (in the io case, start_flow).  Its a  
bit hand wavy on the details, but the idea is that forked concurrent  
state machines could complete without joining, instead they just go  
off to the next state.  The join would happen explicitly with some  
kind of syntax in the state machine definition (join?).

-sam

> Walt
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