[rabbitmq-discuss] RabbitMQ crash due to out of memory

[Chen, Bin]

Hi Matthias,

My system is Windows 2008 Server 64-bit which has 24 GB RAM installed.
Erlang is a 32-bit version.

We had out-of-memory crash before with default HWM (40% - 800 MB).

Since Erlang VM has /LARGEADDRESSAWARE flag set, which implies it can
use up to 4 GB on a 64-bit Windows, we increased HWM to 1.6 GB.
As I pointed out in my previous email, RMQ detects 2GB as the maximum
usable memory in my case, we have to use 80% to set HWM to 1.6 GB.

The memory usage in crash dump may not be trustable. 
I had seen an out-of-memory crash dump before, indicating that Erlang
failed to allocate 1.4 GB of memory.


Best regards,
--Bin Chen


-----Original Message-----
From: Matthias Radestock [mailto:matthias at rabbitmq.com] 
Sent: Tuesday, August 28, 2012 2:01 PM
To: Discussions about RabbitMQ
Cc: Chen, Bin
Subject: Re: [rabbitmq-discuss] RabbitMQ crash due to out of memory

On 28/08/12 21:40, Chen, Bin wrote:
> The version is RabbitMQ 2.8.4 on Erlang R15B01.

Is that the 32-bit or 64-bit version of Erlang? If the former then
please switch to the latter.

> The high memory watermark was set to 1.6 GB. See the attached picture.

When you say "set", do you mean you changed it from the default values?

1.6GB at the default threshold of 40% would imply a detected usable
memory of 4GB, but the crash dump indicates that Erlang failed to
allocate ~40Mb of memory when it had just 2.6GB already allocated. So
either
- the usable system memory was detected incorrectly, or
- the memory HWM was increased from the default, or
- other applications are using the memory, or
- the crash dump significantly underreported the memory usage

Regards,

Matthias.