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<p>You can provoke a VM "crash" with erlang:halt(abort) to test if
the OS creates a core dump file.<br>
</p>
<p><br>
</p>
<p>/Sverker<br>
</p>
<br>
<div class="moz-cite-prefix">On 08/16/2017 05:10 PM, Lukas Larsson
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAP3zBqP8ZGuVm2xU1vOgAe4LJ3SwBZrG6vZ5jJM_yUViFmH=JA@mail.gmail.com">
<pre wrap="">You need to instruct the operating system to save a core dump,
<a class="moz-txt-link-freetext" href="http://man7.org/linux/man-pages/man5/core.5.html">http://man7.org/linux/man-pages/man5/core.5.html</a>.
Some operating systems can be configured to dump parts of the core dump to
the syslog when a segfault happens, which can be useful but a full core
dump contains much more information so is a lot more useful.
Lukas
On Wed, Aug 16, 2017 at 5:00 PM, Gerhard Lazu <a class="moz-txt-link-rfc2396E" href="mailto:gerhard@lazu.co.uk"><gerhard@lazu.co.uk></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">The crash dump was never generated because the Erlang VM segfaulted.
Is there a way to force extra debugging output in segfault scenarios?
On Wed, Aug 16, 2017 at 1:42 PM, Lukas Larsson <a class="moz-txt-link-rfc2396E" href="mailto:lukas@erlang.org"><lukas@erlang.org></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hello,
In order to debug this we need access to a core file generated from the
crash and also the beam.smp binary that was used to run it.
Lukas
On Wed, Aug 16, 2017 at 1:20 PM, Gerhard Lazu <a class="moz-txt-link-rfc2396E" href="mailto:gerhard@lazu.co.uk"><gerhard@lazu.co.uk></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi,
A RabbitMQ 3.6.11-rc.3 node crashed when OTP 20.0.2 segfaulted. This is
the only information that we have about the Erlang VM itself:
Aug 16 04:08:59 localhost kernel: [61139.180699] 2_scheduler[15162]:
segfault at 5c ip 00000000005ba760 sp 00007f8fea1ffc40 err
or 4 in beam.smp[400000+333000]
This is the last line logged by RMQ, 2 seconds before the Erlang VM
segfault:
=INFO REPORT==== 16-Aug-2017::04:08:57 === closing AMQP connection
<0.24230.9> (10.0.16.35:42562 -> 10.0.16.23:5672, vhost: '/', user:
'admin')
beam.smp runs with the following flags:
/var/vcap/packages/erlang-20.0.2/lib/erlang/erts-9.0.2/bin/beam.smp
-W w -A 64 -P 1048576 -t 5000000 -stbt db -zdbbl 128000 -K true -- -root
/var/vcap/packages/erlang-20.0.2/lib/erlang -progname erl -- -home
/home/vcap -- -pa /var/vcap/jobs/rabbitmq-server/packages/rabbitmq-server/ebin
-noshell -noinput -s rabbit boot -sname rabbit@rmq0-rmq-gcp-36 -boot
start_sasl -config /var/vcap/jobs/rabbitmq-server/rabbitmq -kernel
inet_default_connect_options [{nodelay,true}] -sasl errlog_type error -sasl
sasl_error_logger false -rabbit error_logger {file,"/var/vcap/sys/log/rabbi
<a class="moz-txt-link-abbreviated" href="mailto:tmq-server/rabbit@rmq0-rmq-gcp-36.log">tmq-server/rabbit@rmq0-rmq-gcp-36.log</a>"} -rabbit sasl_error_logger
{file,<a class="moz-txt-link-rfc2396E" href="mailto:/var/vcap/sys/log/rabbitmq-server/rabbit@rmq0-rmq-gcp-36-sasl.log">"/var/vcap/sys/log/rabbitmq-server/rabbit@rmq0-rmq-gcp-36-sasl.log"</a>}
-rabbit enabled_plugins_file "/var/vcap/jobs/rabbitmq-serve
r/packages/rabbitmq-server/etc/rabbitmq/enabled_plugins" -rabbit
plugins_dir "/var/vcap/jobs/rabbitmq-server/packages/rabbitmq-server/plugins"
-rabbit plugins_expand_dir "/var/vcap/store/rabbitmq-serv
er/mnesia/rabbit@rmq0-rmq-gcp-36-plugins-expand" -os_mon start_cpu_sup
false -os_mon start_disksup false -os_mon start_memsup false -mnesia dir
"/var/vcap/store/rabbitmq-server/mnesia/rabbit@rmq0-rmq-gcp-36" -kernel
inet_dist_listen_min 25672 -kernel inet_dist_listen_max 25672
We are running on:
4.4.0-83-generic #106~14.04.1-Ubuntu SMP Mon Jun 26 18:10:19 UTC
2017 x86_64 GNU/Linux
When this happens again, how do I capture more debugging information? I
would like to file an OTP bug report, but I'm not sure that we have enough
information.
Apparently, this was reported at least once before, against OTP 18.1:
<a class="moz-txt-link-freetext" href="https://github.com/rabbitmq/rabbitmq-server/issues/459">https://github.com/rabbitmq/rabbitmq-server/issues/459</a>
Thank you, Gerhard.
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