[erlang-questions] unregistering a process during takeover

[Nuku Ameyibor]

>
> When did you run application:info() on b and saw the application running
> there? Was it after killing a?

    i run that function on node b after restarting  node node a and making
it takeover from the failover node b.
    and i make a mistake it wasn't running on node b but on node a .


To be clear, your config says the application should failover to *either* b
> or c.

   yes true and that is what happens .

  but how do errors during restarts affect the distribution  mechanism .
  for instance how do global name clashes affect the distribution mechanism
.
  i got this error during takeover but the takeover still happened
 thanks !!

On Sat, Jan 24, 2015 at 12:53 PM, Nuku Ameyibor <nayibor@REDACTED> wrote:

> When did you run application:info() on b and saw the application running
>> there? Was it after killing a?
>
>     i run that function on node b after restarting  node node a and making
> it takeover from the failover node b.
>     and i make a mistake it wasn't running on node b but on node a .
>
>
> To be clear, your config says the application should failover to *either*
>> b or c.
>
>    yes true and that is what happens .
>
>   but how do errors during restarts affect the distribution  mechanism .
>   for instance how do global name clashes affect the distribution
> mechanism .
>   i got this error during takeover but the takeover still happened
>  thanks !!
>
>
>
> On Fri, Jan 23, 2015 at 9:30 PM, Ulf Wiger <ulf@REDACTED> wrote:
>
>> My comment about the boot script was just because I didn’t see a -boot
>> option in your command line.
>>
>> When did you run application:info() on b and saw the application running
>> there? Was it after killing a?
>>
>> To be clear, your config says the application should failover to *either*
>> b or c.
>>
>> BR,
>> Ulf W
>>
>>
>> On 23 Jan 2015, at 20:58, Nuku Ameyibor <nayibor@REDACTED> wrote:
>>
>>
>>
>> Dear ulf ,
>>
>> I used retool.config to create the release.   i run the executables
>> created to run the application and added -c option for da various nodes .
>> I did start the executables on node b cuz i had sync_nodes_mandatory
>> option and a restart/run of app on node a  requires  node  b and c to be
>> running .
>> I also run application:info() on b and saw the application running on b
>> It was however not running on node c due to the takeover .
>> Had to create a new shell on node c .
>>
>> Anyway i will try again and  note u suggestions  about rebar ,relx ,setup
>> .
>> Thanks a lot !!!
>>  ------------------------------
>> From: Ulf Wiger <ulf@REDACTED>
>> Sent: ‎23/‎01/‎2015 17:49
>> To: Nuku Ameyibor <nayibor@REDACTED>
>> Cc: erlang questions <erlang-questions@REDACTED>
>> Subject: Re: [erlang-questions] unregistering a process during takeover
>>
>> Not sure based on what you’ve described. A possibility is that you’ve
>> forgotten to start the application on b.
>>
>> The next step, though, would be to also use a boot script. You could use
>> rebar, relx, OTP systools or my personal pet project, setup [1].
>>
>> Using a boot script, your applications are started automatically, or in
>> the case of distributed apps, at least prepared to start, so that
>> failover/takeover can work.
>>
>> BR,
>> Ulf W
>>
>> [1] http://github.com/uwiger/setup
>>
>> https://github.com/uwiger/setup/wiki/Example%3A-generating-boot-scripts-from-a-running-system
>> <https://github.com/uwiger/setup/wiki/Example:-generating-boot-scripts-from-a-running-system>
>>
>>
>> On 23 Jan 2015, at 12:09, Nuku Ameyibor <nayibor@REDACTED> wrote:
>>
>> hi ulf ,
>> thanks.
>> the takeover is working okay now  !!! .
>> config a is this
>>
>> [{kernel,
>>   [{distributed, [{m8ball,
>>                    5000,
>>                   [a@REDACTED, {b@REDACTED, c@REDACTED}]}]},
>>    {sync_nodes_mandatory, [b@REDACTED, c@REDACTED]},
>>    {sync_nodes_timeout, 30000}
>>   ]
>>  }
>> ].
>>
>> i start each node with
>> bin\werl.exe -sname c -config
>> C:\wamp\www\erlang\proj\m8ball\apps\m8ball_1_0_0\config\c.config
>>
>> there are 3 nodes .their conf files are similar with sync_nodes_mandatory
>> being slightly different .
>>
>> a small question .
>> the first round of  failover and takeover seems to work fine .
>> but after the first round (start node a,b,c  . kill a  b does failover
>> .kill b c does failover . restart a,b  a does takeover from c killing c
>> application on c .i restart shell on c  )
>>
>> * after the first round when  i try to do a failover   onto b by killing
>> a it doesnt work .*
>> was wondering how come since the first round of failover take over worked
>> fine .
>>
>>
>>
>>
>> On Fri, Jan 23, 2015 at 6:35 AM, Ulf Wiger <ulf@REDACTED> wrote:
>>
>>>
>>> On 23 Jan 2015, at 03:44, Nuku Ameyibor <nayibor@REDACTED> wrote:
>>>
>>> =INFO REPORT==== 23-Jan-2015::02:20:57 ===
>>> global: Name conflict terminating {m8ball_server,<2910.62.0>}
>>>
>>>
>>> This suggests that you’re connecting the nodes *after* starting your
>>> applications, so that the application processes have time to globally
>>> register themselves first. Global detects the name conflict when trying to
>>> merge the registries of the two nodes.
>>>
>>> You can for example use the ‘distributed’ option, described here:
>>> http://www.erlang.org/doc/apps/kernel/application.html#load-1
>>>
>>> and here:
>>>
>>> http://www.erlang.org/doc/man/kernel_app.html
>>>
>>> BR,
>>> Ulf W
>>>
>>> Ulf Wiger, Co-founder & Developer Advocate, Feuerlabs Inc.
>>> http://feuerlabs.com
>>>
>>>
>>>
>>>
>>
>> Ulf Wiger, Co-founder & Developer Advocate, Feuerlabs Inc.
>> http://feuerlabs.com
>>
>>
>>
>>
>> Ulf Wiger, Co-founder & Developer Advocate, Feuerlabs Inc.
>> http://feuerlabs.com
>>
>>
>>
>>
>
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