[erlang-questions] How to diagnose stuck Erlang node

Ahmed Omar <>
Fri Oct 28 10:30:17 CEST 2011

Are you able to expand message queue of user_drv process? That might give
some information.
Did you check epmd status before dumping?

On Fri, Oct 28, 2011 at 10:10 AM, Kirill Zaborsky <> wrote:

> Just 2 days passed and Erlang node got stuck once again.
> This time I killed it with SIGUSR1 and received a crash dump.
> Checking all the logs on host didn't bring any hints where the problem may
> be.
> And in crash dump the only suspicious thing is that user_drv has message
> queue length equal to 7550. The program counter points
> to user_drv:server_loop/5 + 48 - is there any way to get info what
> instruction in the source code it corresponds to?
> BTW crash dump viewer says that crash dump was truncated is there any way
> to get full crash dump?
> The system is running R14B03 if it matters.
> Any advices are welcomed.
> Kind regards,
> Kirill Zaborsky
> 2011/10/26 Kirill Zaborsky <>
>> Recently we have found some problems with our Erlang application:
>> For some time system works ok (e.g. before today it run with no problems
>> for at least 17 days). Then something happens and it "stucks". It does not
>> repond to pings, http interface (mochiweb) gives no replies. The only thing
>> that can be observed is standard "ALIVE" message sent to stdout every 15
>> minutes when there is no output to stdout. Messages from logs show nothing
>> special before logging stops.
>> The only thing I could do is just kill the emulator. That gives me
>> opportunity to restart the system but gives no additional information about
>> the roots of the problem.
>> On JVM it's possible to get program thread dump (using QUIT signal) is
>> there some ways to "manually" force Erlang emulator to produce crash dump
>> without using erlang:halt/1?
>> Are there some other ways to diagnose this problem which I should take a
>> look at?
>> Kind regars,
>> Kirill Zaborksy
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Best Regards,
- Ahmed Omar
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@spawn_think <http://twitter.com/#!/spawn_think>
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