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Subject: Re: Sv: Named pipes and multiple writers
To: Ken Brown <kbrown AT cornell DOT edu>, cygwin <cygwin AT cygwin DOT com>
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From: Norton Allen <allen AT huarp DOT harvard DOT edu>
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Date: Thu, 26 Mar 2020 13:00:20 -0400
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On 3/26/2020 12:44 PM, Ken Brown via Cygwin wrote:
> On 3/26/2020 12:03 PM, Norton Allen wrote:
>> On 3/26/2020 11:11 AM, Ken Brown via Cygwin wrote:
>>>
>>> BTW, I've been working on adding support for multiple readers.  I 
>>> expect to have a first cut ready within a week or two.  Would you 
>>> have any use for that?  If so, I could revive the topic/fifo branch 
>>> and push my patches there for you to test.
>>>
>>
>> Ken, what are the semantics for multiple readers? Do all readers see 
>> the same data,  or is it first come first served or something else?
>
> It's first come, first served.  If two readers attempt to read 
> simultaneously, it's possible that one will get some of the available 
> input and the other will get some more.
>
> The only use case for multiple readers that I've come across of is 
> Midnight Commander running under tcsh.  I didn't dig into the code 
> enough to know why they do it, or why only under tcsh.  See
>
> https://sourceware.org/pipermail/cygwin/2019-December/243317.html
>
> and
>
> https://cygwin.com/pipermail/cygwin-apps/2019-December/039777.html
>
> That's what got me interested in this.  It would be nice to know if 
> there are other use cases.
>
I suppose it could be used as a simple approach to deploying jobs to 
worker processes, provided a process could guarantee that it received 
enough information to define a job and not more than one. I guess if the 
job definition were fixed length that could work.


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