[rabbitmq-discuss] Help with my rabbitmq crashing

Geocast info at geocast.net
Tue Oct 9 10:31:18 BST 2012

Hello Emile,

Thanks for your kind answer. This is my test:

root at rabbitmq2:~# free -m
             total       used       free     shared    buffers     cached
Mem:          8004        452       7551          0          9         88
-/+ buffers/cache:        354       7649
Swap:            0          0          0
root at rabbitmq2:~#
root at rabbitmq2:~# erl
Erlang R15B01 (erts-5.9.1) [source] [64-bit] [smp:8:8]
[async-threads:0] [kernel-poll:false]

Eshell V5.9.1  (abort with ^G)
1> size(<<0:2850821240/unit:8>>).

Crash dump was written to: erl_crash.dump
binary_alloc: Cannot allocate 5701642511 bytes of memory (of type "binary").

It seems so strange, why the memory allocation fails though there is
enough free memory there?

Thanks again.

2012/10/9 Emile Joubert <emile at rabbitmq.com>:
> Hi,
> On 09/10/12 08:10, Geocast wrote:
>> This rabbitmq has been running for long days without problems.
>> Today I restarted it but failed. The info:
>> root at rabbitmq2:/var/log/rabbitmq# cat startup_err
> The reason for the broker crashing in the first place is more likely to
> be in the main broker logfile or the broker sasl file. You should look
> at that also.
>> Crash dump was written to: erl_crash.dump
>> eheap_alloc: Cannot allocate 2850821240 bytes of memory (of type "heap").
>> Aborted
> I assume the quoted error was generated upon attempted startup after the
> crash. The crash would have caused the broker to stop in such a way that
> an expensive and lengthy recovery process is required at startup, in
> order to recover messages.
>> root at rabbitmq2:/var/log/rabbitmq# free -m
>>              total       used       free     shared    buffers     cached
>> Mem:          8004       1242       6761          0         13        870
>> As you see, my system has enough free memory, but rabbitmq aborted in
>> the process of starting.
> It does looks like there is enough free memory and that allocation
> should succeed, but this depends on when the "free" command was run.
> There may have been less free memory while the broker was trying to
> start up. Is there any other reason why the OS might refuse? Are there
> any ulimits in effect that might prevent it? Does the OS syslog say
> anything? The root user might not be subject to the same limit, so it
> might be worth running the broker as root, just to start up.
> Can you get Erlang to allocate that much memory independently from the
> running the broker? Try this test - start an Erlang VM
>  erl
> and enter this:
>  size(<<0:2850821240/unit:8>>).
> The result should be 2850821240. If you receive an error instead then
> the broker is unlikely to have enough RAM to recover messages at startup.
> -Emile

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