It would appear Google Groups ate my reply; thus, this resend. Sorry if this is a dup for anyone.<br><div class="gmail_quote">--------------------<br><br>
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On 5/29/2012 6:21 AM, Tony Garnock-Jones wrote:
</div><blockquote type="cite"><div class="im">On 28 May 2012 19:12, Reverend Chip <span dir="ltr"><<a href="mailto:rev.chip@gmail.com" target="_blank">rev.chip@gmail.com</a>></span> wrote:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>That's very funny.</div>
If you're serious, then I can't take you seriously.<br>
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</div><div>I suspect you're just being rude....</div></div></blockquote>
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I explained a scenario, as produced by the current flow control
code, that is ridiculous on its face: That growing queues are fine,
until consumers appear, at which point growing queues are not fine.
That's a paradoxical result that at the very least should prompt
reevaluation of the flow control algorithm. To ask what the
practical bad results are in my specific case is ridiculous
misdirection.<br>
<br>
Either growing queues (up to disk and memory limits) are acceptable
-- my position, and the position of RMQ without consumers -- or
growing queues are not acceptable -- the position of RMQ with
consumers. This paradox is quite simple to write and to read. The
behavior of the current code is absurd, as anyone can see if they
were to choose to look.<br>
<br>
So no, I was not being rude, specifically. But I did ridicule your
comment, which well deserved it. Per Thomas Jefferson: "Ridicule is
the only weapon which can be used against unintelligible
propositions. Ideas must be distinct before reason can act upon
them."<br>
<br>
PS: You may not have thought about the further wrinkle that the
queues do not accept new messages until they are EMPTY. Which is
doubly ridiculous.<div><div class="h5"><br>
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<div>, but since it's also possible that the message you're
replying to didn't get through to you in its entirety (because
of broken "From" quoting at some stage in the mail delivery
pipeline), I'll reproduce the rest of what I wrote here in
case it helps advance the discussion:</div>
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<div>>From one point of view, any time consumers exist
but are not keeping up with offered traffic is a good time to
throttle the producers. Perhaps call this the "steady state"
point of view - I'm unsure if it has a better name already.</div>
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<div>>From another point of view - call this the
"bursty" point of view, perhaps - the growth of queues is
perfectly acceptable, whether consumers exist at the time or
not.</div>
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<div>ISTM Rabbit makes a guess about whether the
application is "steady state" or "bursty", choosing "steady
state" all the time. Rabbit team, is this the case? Is there a
way of configuring the flow control to permit unbounded queue
growth to support the "bursty" case? Or do I have the wrong end
of the stick entirely?</div>
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<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div>1. A client is publishing 1.5K/sec to each of four
exchanges, each of which has a queue.</div>
<div>2. There are no consumers. Therefore the queue is
growing.</div>
<div>3. RMQ does not stop this. "Flow control" does not
trigger.</div>
<div>4. The consumers appear to begin to tear down the
backlog.</div>
<div>
5. RMQ per-connection flow control suddenly decides that now
there are some consumers, now it has a reason to throttle
the sender.</div>
<div>6. If the consumers had not shown up, the producer would
not have been blocked.</div>
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<div>7. The consumers drain some of the messages from the
queues.</div>
<div>8. The producers are unblocked.</div>
<div>9. Profit!!!</div>
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<div>Regards,</div>
<div> Tony</div>
-- <br>
Tony Garnock-Jones<br>
<a href="mailto:tonygarnockjones@gmail.com" target="_blank">tonygarnockjones@gmail.com</a><br>
<a href="http://homepages.kcbbs.gen.nz/tonyg/" target="_blank">http://homepages.kcbbs.gen.nz/tonyg/</a><br>
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