<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif; "><div>We use python - a process normally has several channels open, using pika.SelectConnection and the continuation (event-driven) programming style.</div><div><br></div><div>However, we typically use a channel per queue partly so that we can set prefetch on a per queue basis.</div><div><br></div><div>So I think it would make more sense for the prefetch limit to be associated directly with the queue.</div><div><br></div><div>Michael</div><div><br></div><span id="OLK_SRC_BODY_SECTION"><div style="font-family:Calibri; font-size:11pt; text-align:left; color:black; BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; PADDING-BOTTOM: 0in; PADDING-LEFT: 0in; PADDING-RIGHT: 0in; BORDER-TOP: #b5c4df 1pt solid; BORDER-RIGHT: medium none; PADDING-TOP: 3pt"><span style="font-weight:bold">From: </span> Alvaro Videla <<a href="mailto:videlalvaro@gmail.com">videlalvaro@gmail.com</a>><br><span style="font-weight:bold">Reply-To: </span> rabbitmq <<a href="mailto:rabbitmq-discuss@lists.rabbitmq.com">rabbitmq-discuss@lists.rabbitmq.com</a>><br><span style="font-weight:bold">Date: </span> Monday, March 18, 2013 1:36 PM<br><span style="font-weight:bold">To: </span> rabbitmq <<a href="mailto:rabbitmq-discuss@lists.rabbitmq.com">rabbitmq-discuss@lists.rabbitmq.com</a>><br><span style="font-weight:bold">Subject: </span> Re: [rabbitmq-discuss] basic.qos prefetch across multiple queues - useful?<br></div><div><br></div><div><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><div><div dir="ltr"><div style="">Hi,</div><div style=""><br></div>
I think per-queue would be better, at least for the PHP people. Since PHP doesn't support threads is not common to have multiple channels in one process. So basic.qos as is today limits every queue in the channel for most PHP scripts.
<div><br></div><div style="">I guess other languages like Python are in the same area.</div><div><br></div><div style="">Regards,</div><div style=""><br></div><div style="">Alvaro</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Mar 18, 2013 at 7:30 PM, Matthias Radestock <span dir="ltr">
<<a href="mailto:matthias@rabbitmq.com" target="_blank">matthias@rabbitmq.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Is anybody setting a basic.qos prefetch limit on channels with consumers on multiple queues?<br><br>
If so, are you relying on the fact that the prefetch limit applies *across* queues rather than *per* queue?<br><br>
That feature entails considerable implementation complexity and has a substantial performance impact on consuming from basic.qos-limited channels in general. And I've just found a bug in that area of the code, fixing of which will make the implementation even
more complex and hurt performance even more.<br><br>
Hence I am trying to gauge people's opinion on whether we could make the prefetch limit apply per-queue instead.<br><br>
Regards,<br><br>
Matthias.<br>
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