[rabbitmq-discuss] RabbitMQ 'hang' when trying to access HA queues

Thu Sep 12 11:41:25 BST 2013

Hi,

You asked:

> Was there anything unusual in the logs?

No. This was what was most disconcerting about this issue. We have done many many hours of testing under very high loads with multiple failure scenarios and whenever there has been an issue there has always been something in the log files which gave some indication of the problem. In this case the only entries we could see in the log files were the aborted connection reports from rabbitmqctl (I assume when it was cancelled by the operator).

>"queues hang" is not the signature of any bug we've fixed since 2.7.1. 
> However, it is unlikely that you have stumbled on a new problem. Odds are that whatever causes the hang is no longer present in the most recent rabbit releases.

It's a shame that this issue was not explicitly resolved since 2.7.1 as it would have eased the minds of the various parties involved in the investigation. Would it be correct to say that since 2.7.1 there has been major rewrites of the HA queue implementation and given the strong advice for users to upgrade to 2.8 and beyond, it is probable there were very few people using 2.7.1 in HA mode so a defect might have remain undiscovered? I appreciate this sort of question is impossible to answer without a significant amount of conjecture so any answer would be based on 'gut feeling'. 

Regards, Andrew.

-----Original Message-----
From: Matthias Radestock [mailto:matthias at rabbitmq.com] 
Sent: 12 September 2013 11:14
To: Discussions about RabbitMQ
Cc: Andrew Rendell
Subject: Re: [rabbitmq-discuss] RabbitMQ 'hang' when trying to access HA queues

Andrew,

On 11/09/13 15:56, Andrew Rendell wrote:
> Last week, during a very important test, under very low load 
> conditions, suddenly, two queues 'hung'.

Was there anything unusual in the logs?

> What we are hoping is that somebody could give us any indication of 
> what could cause this issue. In an ideal world, somebody would report 
> that this is a known issue with 2.7.1 and that the issue is resolved 
> at a later release.

"queues hang" is not the signature of any bug we've fixed since 2.7.1. 
However, it is unlikely that you have stumbled on a new problem. Odds are that whatever causes the hang is no longer present in the most recent rabbit releases.

Matthias.

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