[erlang-questions] HEART

Michael L Martin <>
Wed May 13 02:59:55 CEST 2015


But who watches the watchdog?


On 05/12/2015 05:37 PM, Miles Fidelman wrote:
>> On Mon, May 11, 2015 at 9:13 PM, Roberto Ostinelli <
>> > wrote:
>>
>> >/  In non-erlang systems, I would have standard watchdogs that 
>> launch an
>> />/  application on OS boot, and then monitor it and relaunch it if 
>> necessary.
>> /
>>
>> The heart system in Erlang is a simple watchdog, mostly used if you 
>> nothing
>> else that will restart your application. In an SysV init system, 
>> there is
>> no automatic watching and restart. In RcNG in FreeBSD, there is no 
>> restart.
>> In OpenBSDs rc, there is no automatic restart.
>>
>
> Wait a minute - isn't that what respawn does in a SysV init environment?
>
> Of course that only works if the VM well and truly dies.  If it locks 
> up, you still have a problem.
>
> Anybody see a reason you couldn't:
> 1. start BEAM with respawn
> 2. start a separate watchdog process that periodically runs a few 
> tests to see if BEAM is running properly,
> and if not, KILLs the process - at which point respawn would take care 
> of a restart.
>
> Miles Fidelman
>
>



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